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| ==Contents== | | ==Contents== |
|
| |
| [[Book - Experimental Embryology (1909) 1|Chapter I Introductory]] | | [[Book - Experimental Embryology (1909) 1|Chapter I Introductory]] |
|
| |
|
| [[Book - Experimental Embryology (1909) 2|Chapter II Cell-Division And Growth]] | | [[Book - Experimental Embryology (1909) 2|Chapter II Cell-Division And Growth]] |
| | | # Ce1l-division |
| 1. Ce1l-division
| | # Growth |
| 2. Growth
| |
|
| |
|
| [[Book - Experimental Embryology (1909) 3|Chapter III External Factors]] | | [[Book - Experimental Embryology (1909) 3|Chapter III External Factors]] |
| | | # Grravitation |
| 1. Urrnvitation
| | # Mechanical agitation |
| | | # Electricity and magnetism |
| 2. Mechanical agitation
| | # Light |
| | | # Heat |
| Electricity and magnetism | | # Atmospheric pressure. The respiration of the embryo. |
| | | # Osmotic pressure. The role of water in growth |
| Light | | # The chemical composition of the medium |
| | | # Summary |
| Heat | |
| | |
| Atmospheric pressure. The respiration of the embryo. | |
| | |
| Osmotic pressure. The role of water in growth | |
| | |
| The chemical composition of the medium | |
| | |
| Summary | |
|
| |
|
| [[Book - Experimental Embryology (1909) 4|Chapter IV Internal Factors]] | | [[Book - Experimental Embryology (1909) 4|Chapter IV Internal Factors]] |
|
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|
| (1) The initial structure of the germ as a cause of differentiation. | | (1) The initial structure of the germ as a cause of differentiation. |
| | # The modern form of the preformationist doctrine |
| | # Amphibia |
| | # Pisces |
| | # Amphioxus |
| | # Coe-lenterata |
| | # Ecliinodcrmata |
| | # Nemertinen |
| | # Ctenophora |
| | # Chaetopoda and Mollusca |
| | # Ascidia |
| | # General considerations and conclusions |
| | # The part played by the spermatozoon in the determination of egg-strucure |
| | # The part played by the nucleus in differentiation |
|
| |
|
| 1. The modern form of the prefurmationist doctrine
| | (2) The actions of the parts of the developing organism on one another |
| 2. Amphibia
| |
| 3. Pisces
| |
| 4. Amphioxus
| |
| 5. Coe-lenterata
| |
| 6. Ecliinodcrmata
| |
| 7. Nemertinen . . . . . . . . 204
| |
| 8. (.‘tenopho1':i . . . . . . . . 208
| |
| 9. Chaetopoda and Mollusca . . . . . . 213
| |
| 10. Ascidia . . . . . . . . . 229
| |
| 11. General consiileratious and conclusions . . . 240
| |
| 12. The part. played by the spernmtozoon in the determination of egg-.<ztructm'e . . . . . 247
| |
| 13. The part played by the nucleus in ilifl'e1'enti;iti0n . . 251
| |
| (2) The actions of the parts of the developing oiganism on | |
| one another 271 | |
|
| |
|
| [[Book - Experimental Embryology (1909) 5|Chapter V Driesch’s Theories Of Development - General Reflections And Conclusions]] | | [[Book - Experimental Embryology (1909) 5|Chapter V Driesch’s Theories Of Development - General Reflections And Conclusions]] |
| Line 109: |
Line 97: |
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| APPENDIX A | | APPENDIX A |
| On the .’~y)1)l)lL'l2l'y of the egg, the symmetly of scglnentation, and the symmetry of the embryo in the Frog | | On the symmetry of the egg, the symmetry of segmentation, and the symmetry of the embryo in the Frog |
| | |
|
| |
|
| APPENDIX B | | APPENDIX B |
|
| |
|
| On the part played by the nucleus in (lifferenti:L’tion | | On the part played by the nucleus in differentiation |
| | |
| I.\'m<;x or AUTl{0I{
| |
| | |
| Ixmzx or SUBJPJCTS
| |
| | |
| ADDENDA
| |
| | |
| ==Appendix A==
| |
| | |
| FURTHER REMARKS ON RELATION BETWEEN THE
| |
| SYMMETRY OF THE EGG, THE SYMMETRY OF SEG
| |
| MENTATION, AND THE SYMMETRY OF THE EMBRYO IN
| |
| THE FROG.
| |
| | |
| IN the measurements, referred to above (pp. 165-8), of the
| |
| angles between the plane of symmetry of the egg (as determined by
| |
| the position of the grey crescent), the first furrow and the sagittal
| |
| plane of the embryo, it was found (1) that there was a certain
| |
| tendency for the first furrow and the sagittal plane to coincide,
| |
| since in a. large number of cases small angles preponderated over
| |
| large ones, the standard deviation of this angle from the mean
| |
| (which was practically = 0°) being a- = 40-39° i-65 ; (2) that
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| there was a much greater tendency for the plane of symmetry
| |
| and the sagittal plane to coincide, the standard deviation of the
| |
| angle between these two planes being o'=29-75° _-J; -63 ; (3) that
| |
| the first furrow tended either to coincide with or to lie at right
| |
| angles to the plane of symmetry, the standard deviation about 0°
| |
| being 18-70° i -60, that about 90° being 23-29° j-_ -86, the value
| |
| of 0' for all the observations being 47-90° 1- 1-19. The
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| correlation between the first furrow and the sagittal plane was
| |
| found to be p=-138i -031, that between the plane of symmetry
| |
| | |
| and the sagittal plane p=-372i -025, that between the plane of
| |
| symmetry and the first furrow p=-O87 i -032.
| |
| | |
| These results may be tabulated as follows :
| |
| rr :0
| |
| 40-39° + -65. -138 i -031.
| |
| | |
| tal Plane.
| |
| | |
| Plane of Symmetry and
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| Sagittal Plane. l 2975 -t '63’
| |
| | |
| Plane of Symmetry and
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| First Furrow.
| |
| | |
| First Furrow and Sagit- }
| |
| | |
| .372 i .025.
| |
| | |
| } 47.9oi1.19. .os7¢_.o32.
| |
| | |
| Full details of these results will be found in a paper in
| |
| Biometrika V. 1906.
| |
| | |
| For the purpose of making these measurements the eggs were
| |
| placed in rows parallel to the [mat]; of glass slides, and the
| |
| angles measured between the various planes and lines ruled
| |
| across the slide. Such eggs compress one another by their jelly coats; further, the eggs taken ‘from the uterus were placed
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| haphazard on the slides with the axis making any direction with
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| the vertical. The egg takes about half-an-hour to turn into its
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| normal position with the axis vertical, and during this interval
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| gravity may possibly act upon the yolk and protoplasm, of
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| different specific gravities, and impress a plane of bilateral
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| gravitation symmetry upon the egg, as occurs when the egg is
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| permanently inverted (see above, pp. 82-87). This obliquity of
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| the axis may possibly afiect the relations between the planes,
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| and the mutual compression may also be a disturbing factor,
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| since it is known that in compressed eggs the nuclear spindle is
| |
| perpendicular to the direction of the pressure (pp. 34-36).
| |
| | |
| These angles have therefore now been measured under four
| |
| different conditions:
| |
| | |
| (a) The eggs are close to one another in the rows and the axis is
| |
| horizontal.‘ (Since the rows are parallel to the length of the slide
| |
| the pressure, if any, must be in the same direction, while the
| |
| surfaces of compression or contact are across the slide. The eggs
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| were always so placed that the vegetative poles faced in one
| |
| direction and the planes of ‘ gravitation symmetry ’ were at right
| |
| angles to the length of the slide. This holds good of all the
| |
| following experiments.)
| |
| | |
| (/3) The eggs close, but the. axis vertical with the white pole
| |
| below. In these there can be no gravitation plane of symmetry.
| |
| | |
| (y) The eggs spaced, but the axis horizontal. In these the
| |
| jellies do not touch.
| |
| | |
| (6) The eggs spaced and the axis vertical. In these, therefore,
| |
| both the supposedly disturbing factors are removed. The results
| |
| are given in the following table :—
| |
| | |
| A B C
| |
| | |
| First Furrow and Plane of Symmetry Plane of Symmetry
| |
| Sagittal Plane. and Sagittal Plane. and First Furrow.
| |
| | |
| (.7) .7 = 38-42 g._ -70. .7 = 31-86: -56. .7 = 41-591-_-84.
| |
| ,7 = -201;-028. ,7 = -263;:-_-027. ,7 -= -118;-029.
| |
| (.9) .7 = 33-443-_-56. .7 = 30-17:51. .7 = 39-7l_-1;-61.
| |
| ,7 = 3523-021. .7 = .27si.o22. ,7 = .o23¢.o24.
| |
| (-,) .7 —_- 33-49;:-_-96. .7 = 27-53¢-84. .7 = 36-60: 1-108.
| |
| ,. = .292:-039. —_— -399:-036. p = .075:-043.
| |
| (a) .7 = 31.45133. .7 —_— 26-80¢-82. .7 = 34-46:1-065.
| |
| ,7 —_- -364:-033. ,7 = -451 1.035. ,7 -_- -186;-043.
| |
| | |
| It is evident from this that gravity and ‘ mutual compression ’
| |
| (as I will for the moment term it, though it is doubtful whether
| |
| the pressure has anything at all to do with the result) do affect the
| |
| | |
| magnitude of the angles between these three planes, for in each case the standard deviation falls, while the correlation coeflicient
| |
| rises, when they are both removed. It will be observed that,
| |
| while gravitation (y) has less eflect than compression (3) upon the
| |
| angles B and C, the reverse is the case with the angle A. We
| |
| may be able to find a reason for this later on.
| |
| | |
| There is one point worth noticing. It is quite clear that
| |
| gravity is not indispensable for the development of a grey
| |
| crescent and plane of symmetry, though it is true that the position
| |
| of this plane may be aifected by gravity even in the short interval
| |
| that elapses before the egg turns over.
| |
| | |
| The values for the compressed eggs with horizontal axes (or)
| |
| compare fairly well with those previously obtained, except in the
| |
| case of the plane of symmetry and the first furrow. In the
| |
| former series the latter tended either to coincide with or to lie
| |
| at right angles to the former. In the present series this is not
| |
| the case. This diflerence is probably to be attributed to the
| |
| fact that many of the eggs in the first series must have been
| |
| placed on the slide with the white pole upwards: possibly also
| |
| the ‘ compression ’ was greater then than now.
| |
| | |
| It is fortunate that the same data enable us to study exactly
| |
| the relation between the first furrow and the plane of symmetry
| |
| on the one hand, and the direction of ‘compression’ and of the
| |
| gravitation symmetry plane on the other. It must be remembered that these two are at right angles to one another.
| |
| | |
| Consider first the first furrow.
| |
| | |
| (a) When the eggs are close but the axis horizontal the first
| |
| furrow tends to lie at right angles to the slide, that is, in the
| |
| direction of compression, but at right angles to the gravitation
| |
| symmetry plane. (a-=38-16 i -69.)
| |
| | |
| (fl) When the eggs are close but the axis vertical this tendency
| |
| is not quite so marked. (a'=46-67 i -7' 1.)
| |
| | |
| (y) When the eggs are spaced and the axis horizontal it is
| |
| still there, but slight. (o-=49-32 ;l-_ 1-40.)
| |
| | |
| (6) When the eggs are spaced and the axis vertical the
| |
| direction of the first furrow is random. (zr=52-76¢ 1-17.)
| |
| | |
| VVe may conclude, therefore, that the first furrow tends to lie
| |
| in the direction of the ‘ compression’ and at right angles to the
| |
| plane of gravitation symmetry. The latter tendency, we know,
| |
| exists in forcibly inverted eggs, together with a tendency to lie
| |
| in the plane of symmetry and at 45° to it (above, p. 84).
| |
| Pressure experiments alo show that division is in the direction
| |
| of pressure (p. 34 sqq.).
| |
| | |
| The direction taken up by the plane of symmetry under these
| |
| different circumstances is-quite distinct from that of the first
| |
| furrow. It appears to be determined in the first instance by gravitation, as it usually lies in the gravitation symmetry plane.
| |
| It is not, however, only so determined, for if the eggs (compressed
| |
| and with axi horizontal) be allowed to develop in the light the
| |
| plane of symmetry lies either in the gravitation symmetry plane,
| |
| or in the direction of the incident light (parallel to the length of
| |
| the slide in the experiment , while in the dark it lies only across
| |
| the slide. That this secon effect is due to the light and not to
| |
| the pressure is shown by the fact that it occurs when the eggs
| |
| are spaced, and that it may be made to vary in position by
| |
| varying the position of the slide with regard to the light.
| |
| Light, therefore (ordinary daylight), as well as gravity, can help
| |
| to determine the -position of the plane of symmetry, and when
| |
| the latter is excluded it appears that this plane is placed either
| |
| in or at right angles to the source of light.
| |
| | |
| Light appears to exert no effect u on the first furrow.
| |
| | |
| It is now intelligible why, when 1 these factors are operative,
| |
| the relation between the first furrow and the planes of symmetry
| |
| of egg and embryo should be disturbed, since, in the conditions
| |
| of the experiment, those factors which determine the position of
| |
| the former are at right angles to those on which the direction of
| |
| the latter depends.
| |
| | |
| It still remains for us to inquire into the internal causes of
| |
| the direction of these planes in the egg. Roux, as has been
| |
| pointed out, has asserted that the grey crescent appears on the
| |
| opposite side of the egg to that on which the spermatozoon has
| |
| entered (pp. 80, 165), and further that the point of entry of the
| |
| sperm also determines the meridian of the first furrow, since this
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| either includes the sperm-path, or is parallel to it, or, when it is
| |
| crooked, includes or is parallel to the inner portion or ‘ copulation ’
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| path, which is taken to represent the line of approximation of
| |
| the two pronuclei; the outer part being simply the ‘ penetration’
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| path. Roux also arbitrarily selected a fertilization meridian
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| (meridian of the sperm-entry), and showed that this became
| |
| the ventral side (opposite the grey crescent) later on, as well as
| |
| the ineridian of the first furrow (p. 248).
| |
| | |
| I have been able to accurately investigate—by means of
| |
| sections-—the relation between the fertilization meridian, first
| |
| furrow, and sperm-path in a number of eggs in which the
| |
| direction of the symmetry plane had been previously determined,
| |
| and the results of the measurements of these angles are given
| |
| here. The eggs fall into two series, those which were compressed
| |
| and had their axes horizontal (a), and those which were spaced
| |
| and had their axes vertical, the white pole being below (6). In
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| (a) the gravitation symmetry plane and the direction of compression were at right angles to one another, as before.
| |
| | |
| 8 a
| |
| Meridian of sperm entry a- = 21-02° 1-_ 1-63. o- = 31-04°: 1-34.
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| and first furrow. p = -435 3 -074. 9 =-613 i -038.
| |
| | |
| Meridian of sperm entry 0' = 25-67° i 1-35. 0 = 41-01° 3-_ 1-78.
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| and symmetry plane. p = -302 i -083. / P = -006 1 -061.
| |
| | |
| SP§;§§f:;l3(g;§‘}ff1,§§;“ } . .. .—. 17.94° : 1.15. o‘ = 21.47° 1 -93.
| |
| | |
| From this it is clear that there is a very close relation indeed
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| between the point of entry of the spermatozoon and the direction
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| of the first furrow, especially when the disturbing efiects of pressure and gravity are removed. There is, however, little relation
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| between the sperm meridian and the plane of symmetry even
| |
| under the most favourable circumstances, and when the conditiofis are not favourable the correlation is negligible. There is
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| however (in the 6 series) a considerable correlation (p = -479 i '070)
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| between the sperm-pat/l and the plane of symmetry. It should
| |
| be remembered, however, that all these eggs were exposed to the
| |
| light. From what we know of the eifect of this agent upon the
| |
| direction of the symmetry plane, it would not perhaps be too
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| hold a hazard to surmise that in darkness there would be a
| |
| correlation between the sperm entrance and the plane of symmetr .
| |
| | |
| Eiien after the removal of this disturbance there remain
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| factors which interfere with the completeness of the correlation
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| between these planes; these must probably be looked for in
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| the incomplete radial symmetry of certain eggs—due possibly
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| to pressure in the uterus—and to the slight squeezings and distortions the eggs may be subjected to when they are being taken
| |
| from the Frog.
| |
| | |
| It will be seen that the relation between the sperm-path and
| |
| first furrow is closer than that between the latter and the sperm
| |
| entrance. This is because though the furrow may be placed to
| |
| one side of the entrance point, it may still be parallel to the path ,
| |
| or, if not to the ‘penetration ’ path then to the inner or ‘copulation ’ path, as observed by Roux. This ‘ copulation’ path is
| |
| usually observed when the penetration path is turned away from
| |
| the first furrow, that i, when it has not been directed towards
| |
| the egg-axis.
| |
| | |
| The same data give the position of the point or of entrance
| |
| with regard to the direction of ‘pressure ’ and ‘gravitation
| |
| symmetry’. In the (a) series the sperm tends to enter in
| |
| the direction of ‘pressure’, that is, on that side of the egg on
| |
| which it is in contact with its neighbours. Hardly a single
| |
| spermatozoon enters on that side of the egg on which the white
| |
| pole had been turned up, and very few on the opposite side.
| |
| | |
| It is scarcely possible to suppose that either the compression of
| |
| the egg or the gravitation plane brings the spermatozoa round to
| |
| the side of compression, but it may be imagined that either by
| |
| capillarity or by some chemotactic stimulus the spermatozoa are
| |
| especially attracted to the point where the rapidly swelling coats
| |
| of adjacent eggs come into contact, and that therefore fertilization
| |
| is principally effected upon this side. This explains why the first
| |
| furrow lies so often in this direction. The pressure may of course
| |
| afiect the position of the planes in the egg later on.
| |
| | |
| When the eggs are spaced the sperm enters on any side at
| |
| random.
| |
| The deviation of the sperm entrance from the egg-axis (the
| |
| angle between sperm-entrance radius and egg-axis) varies in the
| |
| two series of observations. When the eggs are spaced and the
| |
| axes vertical, the sperm enters mainly near the equator, never
| |
| near the animal pole; when the eggs are compressed and the axis
| |
| horizontal, usually at about 45° from the axis, though it may
| |
| enter near the pole or near the equator. This difierence obviously
| |
| depends on the diiference in the initial position of the eggs on
| |
| the slide. The deviation has apparently very little effect on any
| |
| of the planes we have been considering.
| |
| | |
| Finally, let us try and gain some conception of the mechanism
| |
| by which the direction of the furrow depends on the point of sperm
| |
| entry. It is apparently quite simple, for the sperm-path is
| |
| directed usually towards the axis, the sperm nucleus travels along
| |
| that path to meet the female nucleus, which is also in the axis,
| |
| the centrosome of the sperm divides at right angles to that path,
| |
| the fertilization spindle is developed between the diverging
| |
| centrosomes and cell-division takes place in the equator of the
| |
| spindle ; the first furrow includes therefore the sperm-path.
| |
| Should, however, the ‘penetration ’ path not be exactly radial,
| |
| for whatever reason, the sperm nucleus turns aside to meet the
| |
| female pronucleus, there is a ‘ copulation’, as distinct from a
| |
| ‘ penetration’ path, the centrosome divides at right angles to
| |
| the former, and this, then, is included in or parallel to the plane
| |
| of the furrow. In those cases in which the sperm-path is parallel
| |
| to the furrow it is always quite close to it, and we may suppose
| |
| perhaps that the first division "has not been quite equal. (The
| |
| division of the centrosomes has not, I believe, been observed in
| |
| the Frog, and the foregoing description has been taken from the
| |
| Axolotl. In this genus the definitive centrosome is formed from
| |
| the sperm nucleus, when the latter has already penetrated some
| |
| little way into the egg.) .
| |
| | |
| The causes of the formation of the grey crescent which marks
| |
| the symmetry plane are not so clear.
| |
| | |
| | |
| Roux describes it as being due to the immigration of superficial pigment. Now we have strong reason for believing that
| |
| both the entrance-funnel——produced when the spermatozoon first
| |
| touches the egg-—and the sperm-sphere are local aggregations of
| |
| watery substance. The accumulation of what appears to be a
| |
| more watery substance about the middle piece which has been
| |
| observed in the Axolotl,appears also to occur in the Frog: at least
| |
| the same formation of large clear vacuoles in the sperm-sphere may
| |
| be seen in the latter as in the former. Should this be actually so,
| |
| we may suppose that the streaming movement centred in the
| |
| entrance-funnel and sperm-sphere is responsible for drawing away
| |
| the pigment from a certain region of the surface; hence the grey
| |
| crescent. The sperm-sphere is on the inner side of the sperm
| |
| nucleus: hence the grey crescent would appear on that side of
| |
| the egg which is opposite to the entrance of the spermatozoon,
| |
| should no disturbance of the streaming movement have taken
| |
| place, and, since the sperm-path is radial, would be symmetrically
| |
| disposed with regard to it. In this case, fertilization meridian,
| |
| sperm-path, grey crescent and plane of symmetry, first furrow,
| |
| and, later on, sagittal plane, would all coincide. There is, as
| |
| we have seen, a very fair correlation between the sperm-entrance
| |
| and the first furrow, and again between the sperm-path and the
| |
| grey crescent. But should some other streaming movement of
| |
| the cytoplasm be set up by the gravitation of the heavy yolk
| |
| particles, or by pressure, or by light, then the relation between
| |
| the two processes, the division of the centrosome which determines the direction of the first furrow, on the one hand, and
| |
| on the other, the streaming movement towards the sperm-sphere
| |
| which determines the position of the grey crescent, would be
| |
| disturbed, and while the entrance point of the sperm might still
| |
| continue to determine, though not so completely, the position of
| |
| the furrow, it might come to be without relation to the symmetry
| |
| of the egg and of the embryo; and this is what is actually
| |
| observed.
| |
| | |
| Though it is diflicult to assign the exact cause of each and
| |
| every deviation from the rule, this much is certain, that however
| |
| they may coincide in ‘typical’ development (I use R0ux’s
| |
| expression), the factors which determine cell-division, and those
| |
| which determine differentiation, may be influenced by different
| |
| external causes in widely diifering ways, and are therefore presumably distinct. Nor does this artificial separation of the two
| |
| processes in any wise prejudice the complete normality of the
| |
| | |
| development of the embryo".
| |
| | |
| | |
| Lillie has shown (Jozmz. Esp. Z002. iii. 1906) that in the egg of
| |
| C’/Iaetopterus there are granules of difierent kinds which pass, in
| |
| segmentation, into definite cells. By means of the centrifuge
| |
| some of these--the endoplasmic—-may be driven to one side of
| |
| the egg, but in whatever position these organ-forming granules
| |
| may be thus artificially placed, the cleavage has the same relation
| |
| to the egg axis (as determined by the polar bodies) as in the
| |
| normal egg. The factors of cell-division are thus separable from
| |
| those of differentiation.
| |
| | |
| To the cases quoted in the summary on pp. 245, 246 might be
| |
| added the various instances in which an egg may be made, by
| |
| heat or pressure or shaking, or in artificial parthenogenesis, to
| |
| segment abnormally and yet give rise to a normal larva.
| |
| | |
| ==Appendix B==
| |
| | |
| ON THE PART PLAYED BY THE NUCLEUS IN DIFFERENTIATION
| |
| | |
| (i) BOVERI has more recently (Zellen-Studim, vi, Jena, 1907)
| |
| published a very elaborate account of the irregularities produced
| |
| by dispermy in Echinoid eggs, in which are brought forward
| |
| | |
| still more facts in proof of the qualitative difference of the
| |
| chromosomes.
| |
| | |
| As has been stated above, p. 263, dispermy is induced by
| |
| the simple expedient of adding a large quantity of sperm to the
| |
| eggs. The following types of dispermy are distinguished.
| |
| | |
| A. Tetracentric, i. e. each sperm centre divides.
| |
| (i) 'I‘etraster, with four spindles.
| |
| | |
| (ii) Double spindle, i. e. the female and one male pronucleus
| |
| lie in one spindle, the other male lies aside in its spindle.
| |
| | |
| B. Tricentric, one sperm centre remaining undivided.
| |
| (i) Triaster, a tripolar figure with three spindles.
| |
| | |
| (ii) Monaster-amphiaster, the undivided sperm centre remaining apart with one sperm nucleus.
| |
| | |
| C. Dicentric, neither sperm centre dividing.
| |
| (i) Amphiaster, a spindle is formed between the two centres.
| |
| | |
| (ii) Double monaster: the centres remain apart, one with
| |
| one male, the other with the other male and the female
| |
| pronucleus.
| |
| | |
| The segmentation of these eggs is as follows.
| |
| | |
| The tetraster divides simultaneously into four, which may
| |
| either lie in one plane if the divisions are meridional, or be tetrahedrally arranged. In the first case another meridional division
| |
| ensues, followed by an equatorial, then ‘eight micromeres are
| |
| formed, eight macromeres, and sixteen mesomeres. In the latter
| |
| case not more than three cells can share in the micromere region
| |
| and only four or six of these are produced. The triaster eggs,
| |
| having divided simultaneously into three (meridionally), subsequently show six micromeres, six macromeres, and twelve
| |
| mesomeres.
| |
| | |
| The segmentation of the double spindle eggs is interesting and
| |
| important. Usually the egg divides across the two spindles
| |
| 312 APPENDIX B
| |
| | |
| into two binucleate cells, but it may divide at once into four, or
| |
| into three, one of which is binucleate. The interest lies in the
| |
| binucleate cells, for they continue to produce uni-nucleate and binucleate cells until the latter divide simultaneously into four,
| |
| and this simultaneous division may sometimes involve an irregular
| |
| distribution of the chromosomes, with fatal consequences to the
| |
| cell. Bovcri had already produced evidence of the evil effects of
| |
| an irregular distribution of the 3 n x 2 chromosomes present in
| |
| triasters and tetrasters. A more detailed account is now given.
| |
| | |
| Of the tripartite (triaster) ova about 8 % on an average produced Plutei. In these larvae three regions may be distinguished
| |
| in the egg by the size of the nuclei (proportional to the number
| |
| of chromosomes) and the boundaries between them may be shown
| |
| to correspond to the divisions between the three blastomeres.
| |
| The form is asymmetrical in skeleton and pigment, but Bovcri
| |
| shows that both sides are normal, as though the larva had been
| |
| compounded of two types such as occur, as individual variations,
| |
| in any culture. It is suggested therefore that the slight differences in the two sides are due to difierences in the two sperms.
| |
| | |
| Some of the larvae have partial defects in skeleton or pigment,
| |
| or the skeleton may be much reduced on one side, or one-third of
| |
| the cells may be pathological, i. e. disintegrate in the segmentation
| |
| cavity, while the remaining two-thirds are sound and sometimes
| |
| symmetrical. In this case it is supposed that the degenerate
| |
| cells had separated from the others at an early stage, and that
| |
| the remainder had had time to recuperate. In others two-thirds
| |
| are degenerate, one-third normal, or all three degenerate. When
| |
| the three blastomeres are isolated and allowed to develop independently, segmentation is partial, with two micromeres, two
| |
| macromeres, and four mesomeres, and often all three develop
| |
| normally up to the blastula stage. After that only one or two,
| |
| rarely all three, become Plutei, the rest giving rise to stereoblastulae or stereogastrulae, full of degenerating cells.
| |
| | |
| The isolated quarters of tetrasters also segment partially
| |
| and normally, but few give rise to Plutei. The whole simultaneously quadripartite eggs only rarely give rise to what may be
| |
| called a Pluteus (2 cases in 1500) ; but very degenerate larvae
| |
| are found, with masses of disintegrating cells inside, which are
| |
| assigned to one of the four blastomeres. Stereogastrulae-—with
| |
| nuclei of all the same size--are frequent.
| |
| | |
| As has been alread mentioned, Bovcri points out that the
| |
| probability of each cell’ of a triaster receiving a complete set of
| |
| the 71. chromosomes of the species when there are 3 n x_2 to be distributed must be greater than‘ that of each cell of tetraster
| |
| obtaining a full complement, and the probability for one isolated cell must be greater than that for the whole egg. What the
| |
| mathematical values of these probabilities are Boveri does not
| |
| know, though he makes an attempt to reckon them—not
| |
| theoretically, but by means of a mechanical apparatus; the
| |
| attempt is not quite successful. The fact, however, remains that
| |
| eight per cent. of the triasters produce normal Plutei, only -06 per
| |
| cent. of the tetrasters. This does not depend on the cells receiving
| |
| too much or too little chromatin (see p. 265), nor again on the
| |
| fact that the ratio between size of nucleus and size of cytoplasm
| |
| (see pp. 268, 269) can only be satisfied by certain definite
| |
| numbers of chromosomes, and the only explanation remaining is
| |
| that for normal development of each and every part the nucleus of
| |
| each cell must contain a complete set of the specific chrosomomes ;
| |
| from which it follows that the chromosomes are qualitatively
| |
| unlike.
| |
| | |
| A word may be said about the double-spindled eggs (Type
| |
| A. i). The larvae from these sometimes show abnormal regions,
| |
| and this is attributed to one or more of the binucleate cells
| |
| having divided with a tetraster and irregular distribution of
| |
| chromosomes. Of all such eggs 50 % gave rise to normal Plutei.
| |
| | |
| The degenerative changes undergone by the nuclei of these
| |
| larvae are of several types, to be associated again with differences
| |
| in the combinations of chromosomes.
| |
| | |
| (ii) Boveri’s experimental proof of the qualitative difference
| |
| of the chromosomes does not of course of itself involve a belief
| |
| in the individuality of these bodies, for if the chromatin is
| |
| concerned in inheritance, it is necessary to suppose that the
| |
| number of qualitatively distinct bodies is far greater than the
| |
| number of chromosomes, and these bodies may be differently
| |
| grouped during each successive resting stage.
| |
| | |
| The hypothesis of the individuality of the chromosomes, i.e. of
| |
| a constancy in the manner of grouping of these particles, rests
| |
| in the first instance on such facts as those observed by Sutton in
| |
| B2-ac/:3/stola, where in the spermatogonia the chromosomes are of
| |
| dilferent sizes, which may however be arranged in pairs, together
| |
| with an odd one or accessory chromosome. 1 In the resting stage
| |
| the accessory chromosome remains apart in a separate vesicle,
| |
| while the large chromosomes lie in separate pockets of the
| |
| nuclear membrane, the small ones, each as a separate reticulum,
| |
| in the main body of the nucleus. In the spermatocyte a number
| |
| of bivalent spiremes appear, which show the same dilferences of
| |
| sizes a the pairs of chromosomes previously, and the accessory
| |
| chromosome.
| |
| | |
| The accessory chromosome passes into two only of the four
| |
| spermatids and is supposed to be a sex-determinant.
| |
| | |
| | |
| Similar facts have been reported by Wilson for several Insects
| |
| (see Joum. Esp. Zool. ii, iii, 1905, 1906). '
| |
| | |
| Wilson finds constant size differences between pairs of chromosomes, and either an accessory odd chromosome (which passes
| |
| into only one half of the germ cells) or a pair of idio-chromosomes of unequal size (one of which goes to one half, the other to
| |
| the other half of the spermatozoa), or both the accessory and the
| |
| idio-chromosomes (giving four kinds of spermatozoa). The idiochromosomes are supposed, again, to play a part in sex-determination. Several other observers have found these accessory
| |
| chromosomes, idio-chromosomes, and pairs of chromosomes of
| |
| difierent sizes in various Insects (Boring, Journ. E211. Zool. iv.
| |
| 1907 ; Stevens, ibid. ii. 1905, v. 1908; McClung, Biol. Bull. iii.
| |
| 1902, ix. 1905; Montgomery, Biol. Bull., vi. 1904; Baumgartner, Biol. Bull. viii. 1904-5 ,- Zweiger, Zool. Anz. xxx. 1906;
| |
| Nowlin, Jomw. Exp. Zool. iii. 1906); in Spiders (Wallace, Biol.
| |
| Bull. viii. 1904»-5 ; Berry, Biol. Bull. xi. 1906); and in Myriapods (Blackman, Biol. Bull. v. 1903 ; Medes, Biol. Bull.
| |
| ix. 1905).
| |
| | |
| It is a noteworthy fact that the accessory chromosome retains
| |
| its individuality in the resting stage (looking like a chromatin
| |
| nucleolus), while the others break up. The belief in the individuality of these others rests therefore on the constancy of the relative sizes from generation to generation.
| |
| | |
| Further support for the hypothesis may be derived from theoretical speculations. VVe know that only 2; (one-half the normal
| |
| number) chromosomes are necessary for normal development
| |
| provided that they comprise a complete set. In sexual reproduction n maternal unite with n paternal. A study of the reducing division shows that 1: whole chromosomes first pair with
| |
| and are then separated from or whole chromosomes, and that
| |
| when they dilfer in size those of the same size pair together, and
| |
| it looks as though paternal were here separated from maternal,
| |
| though the distribution of paternal and maternal to the two cells
| |
| will difier, almost certainly, in diiferent cases.
| |
| | |
| If the particles of which the chromosomes are composed are
| |
| also to be paired and separated, it would appear to be necessary
| |
| that their groupin should be constant, in other words that the
| |
| chromosomes shou d retain their individuality.
| |
| | |
| (iii) A case of heterogeneous fertilization between eggs of Seaurchins and the sperm of Anletlon has been described above
| |
| (p. 262). Loeb has recently succeeded in rearing Plutei from
| |
| the eggs of Slrongylocmlrolue fertilized by the sperm of a
| |
| Mollusc (0/lloroaloma). Cytological details are not given (Arc/E.
| |
| Eul. Mecfi. xxvi. 1908). ‘
| |
| | |
| | |
| ==Index Of Authors==
| |
| | |
| Agassiz: effects of fertilization in Ctenophors, 250.
| |
| | |
| Aristotle: theory of development, 13.
| |
| | |
| — the soul in function and development, 292 sqq.
| |
| | |
| — mechanism and teleology, 296.
| |
| | |
| Auerbach :' segmentation of Ascuris
| |
| nigrovenosa, 33.
| |
| | |
| von Baer, 16.
| |
| | |
| Balfour: effect of yolk on segmentation, 29, 88.
| |
| | |
| Bataillon: monstrosities
| |
| osmotic pressure, 120, 135.
| |
| | |
| —- artificial parthenogenesis, 124.
| |
| | |
| Bergh: cell-division in germ-bands
| |
| of Crustacea, 34.
| |
| | |
| Berthold: surface-tension and celldivision, 41, 42.
| |
| | |
| Bischofl‘, 16.
| |
| | |
| Blane: effect of light upon the
| |
| development of the Chick, 94, 96.
| |
| | |
| Boas: rate of growth in man, 63.
| |
| | |
| — change of variability, 73, 74.
| |
| | |
| — diminution of correlation coefiicient, 75.
| |
| | |
| Bonnet : emboitement, 14.
| |
| | |
| — preformation, 15.
| |
| Bonnevie : diminution of chromosomes in Ascaris lumbricoidcs, 258.
| |
| Born : gravity and development, 18,
| |
| 88-85.
| |
| | |
| — pressure experiments on Frogs’
| |
| eggs, 34, 35.
| |
| | |
| Boveri : early development of Slrongylocentrotus, 23, 183-185.
| |
| | |
| — egg of Strongylocentrotus stretched,
| |
| 39.
| |
| | |
| — suppression of micromeres in
| |
| Strongylocentrotus, 186.
| |
| | |
| -— causes of the pattern of segmentation, 197.
| |
| | |
| — karyokinetic plane, sperm path,
| |
| :11 ng first furrow in Strongylocentrotus,
| |
| | |
| 8 .
| |
| | |
| — potentialities of? animal and vegetative cells, 192.
| |
| | |
| — stratification of cytoplasmic substances, 242, 280.
| |
| | |
| -- characters dependent on cytonlmam in Flnhinnid larvae. 261.
| |
| | |
| due to
| |
| | |
| Boveri : diminution of chromosomes
| |
| in Ascaris megalocephala, 252, 255-257.
| |
| | |
| — due to a difference in the cytoplasm, 257.
| |
| | |
| — hybrid larva from enucleate egg
| |
| fragment with characters of male
| |
| parent, 253, 258-260.
| |
| | |
| — irregular distribution of chromosomes a cause of abnormality, 253,
| |
| 263-266.
| |
| | |
| — individuality of chromosomes and
| |
| chromatin, 256, 263.
| |
| | |
| —part played by nucleus in differentiation, 266, 285.
| |
| | |
| —possiblo significance of reducing
| |
| divisions, 266.
| |
| | |
| — number of chromosomes, size of
| |
| nucleus, and size of cell, 68, 267,
| |
| 268.
| |
| | |
| —2méclear division not qualitative,
| |
| | |
| 6 .
| |
| | |
| Bowditch: rate of growth in man,
| |
| 63.
| |
| | |
| -- change of variability, 73.
| |
| | |
| Brauer : Branchipus, 22, 24.
| |
| | |
| Brooks: Lucifer, 22.
| |
| | |
| de Butfon : Preformation, 15.
| |
| | |
| Bullzt: artificial parthenogenesis,
| |
| 12 .
| |
| | |
| Bumpus: change of variability in
| |
| Litlorina, 71, 72.
| |
| | |
| Bunge: respiration of Ascaris, 112.
| |
| | |
| Castle : see Davenpofl: and Castle.
| |
| | |
| Chabry: segmentation furrows and
| |
| embryonic axes in Ascidians, 229.
| |
| | |
| —- development of isolated blastemeres in Ascidians, 229, 230.
| |
| | |
| Child : critique of Driesch’s vitalism,
| |
| 292, note.
| |
| | |
| Chun : isolated blastomeres of Ctenophora, 209.
| |
| | |
| Conklin: maturation, fertilization,
| |
| and development of Cynthia, 230236.
| |
| | |
| — development of isolated blastemeres in Oyntlzia, 237.
| |
| | |
| — development of pieces of gastrula
| |
| in Cynthia, 238.
| |
| | |
| — streaming movements of protonlnsm. 40.
| |
| 316 INDEX OF
| |
| | |
| Crampton : isolated blastomeres of
| |
| Ilycmesaa, 215, 216.
| |
| | |
| — efieot of removal of the polar lobe,
| |
| 217.
| |
| | |
| Dareste: mechanical agitation of the
| |
| Hen’s egg, 89.
| |
| | |
| — electricity, 91.
| |
| | |
| Davenport : catalogue of ontogenetic
| |
| processes, 4 sqq.
| |
| | |
| — definition of growth, 58.
| |
| | |
| — rate of growth, 69.
| |
| | |
| — the role of water in growth, 58,
| |
| 59, 115, 116.
| |
| | |
| - and Castle : acclimatization of eggs
| |
| of Bufo to heat, 100.
| |
| | |
| Delage : causes of artificial parthenogenesis, 124.
| |
| | |
| -- number of chromosomes in artificial parthenogenesis and in merogony, 125.
| |
| De Vries : importance of potassium
| |
| for turgor of plant-cells, 146.
| |
| | |
| Doncaster: hybrid Echinoid larvae,
| |
| 26].
| |
| | |
| Driesch: effect of light in development, 94.
| |
| | |
| — abnormal segmentation in Erhinus
| |
| produced by heat, 105.
| |
| | |
| — Anenteria, produced by heat,
| |
| 106.
| |
| | |
| —- segmentation made irregular by
| |
| dilution of sea-water, 118.
| |
| | |
| —— pressure experiments on Echinoid
| |
| eggs, 37, 38, 185, 240.
| |
| | |
| —- cell-division suppressed by pressure and dilute sea-water, 55; and
| |
| by heat, 105.
| |
| | |
| —nuclear division not qualitative,
| |
| 186.
| |
| | |
| — blastomeres disarranged, 187, 188.
| |
| | |
| — isolated blastomeres of Echinoids,
| |
| 190, 191, 193, 194.
| |
| | |
| — potentialities of animal and vegetative cells, 193, 194, 201, 242, 243.
| |
| | |
| — fragments of blastulae and gastrulae in Echinoderms, 194.
| |
| | |
| — potentialities of ectoderm and
| |
| agghenteron, and their limitations,
| |
| 1 .
| |
| | |
| — development of egg fragments of
| |
| Echinoids, 195, 196.
| |
| | |
| — germinal value, surface-area of
| |
| larvae, and number of cells, 197199, 269.
| |
| | |
| — one larva from two blastulae, 202.
| |
| | |
| — and Morgan : isolated blastomeres
| |
| of Ctenophora, 210, 211.
| |
| | |
| —2e1gg-fragments of Ctenophora, 30,
| |
| | |
| 2!
| |
| | |
| AUTHORS
| |
| | |
| Drgggchz development of Myzostoma,
| |
| | |
| — isolated blastomeres and parts of
| |
| larvae in Phallusia, 288, 289.
| |
| | |
| — first furrow and sagittal plane in
| |
| Echinoids, 250.
| |
| | |
| — characters which depend on cytoplasm in Echinoid larvae, 261, 262.
| |
| | |
| — number of organ-forming substances in cytoplasm, 246, 284,
| |
| 286.
| |
| | |
| —— theory of egg-structure, 281, 286,
| |
| 292.
| |
| | |
| — reason for limitation of potentialities, 192-194, 201, 212, 242, 243,
| |
| 281, 282, 284, 291.
| |
| | |
| --fate a function of position, 188,
| |
| 282.
| |
| | |
| —- return of displaced mesenchyme
| |
| cells in Echinus, 274.
| |
| | |
| - stimuli in ontogeny, 20, 277, 28"284.
| |
| | |
| — part played by nucleus in differentiation, 266, 284, 285.
| |
| | |
| —— equipotential and inequipotentiul
| |
| systems, 176, 277, 285.
| |
| | |
| — rhythm of development, 3.
| |
| | |
| —- harmony of development, 284.
| |
| | |
| —- composition in development, 3,
| |
| 285.
| |
| | |
| — self-difierentiation, 284.
| |
| | |
| —- teleology, static, 286, 291, 292,
| |
| 297.
| |
| | |
| — —- dynamic, 291, 292, 297.
| |
| | |
| — vitalism, 20, 289 sqq.
| |
| | |
| Edwards : physiological zero for
| |
| Home egg, 102.
| |
| | |
| -- growth without differentiation,
| |
| 104.
| |
| | |
| Endres and Walter : post-generation
| |
| of missing half-embryo, 171.
| |
| | |
| Eycleshymer: first furrow
| |
| sagittal plane in Necturus, 168.
| |
| | |
| and
| |
| | |
| Fabricius : views on development,
| |
| 13.
| |
| | |
| Fasola : electric currents, 91.
| |
| | |
| Fehling : growth of the human
| |
| embryo, 59, 60, 63.
| |
| | |
| Feré : effect of sound-vibrations upon
| |
| the Chick, 90.
| |
| | |
| _ ._ of light, 96.
| |
| | |
| — malformations due to high temperatures, 105. .
| |
| | |
| —- need of oxygen for the Chick, 109.
| |
| | |
| —— monstrosities produced by various
| |
| chemical reagents, 18,2.
| |
| INDEX OF AUTHORS
| |
| | |
| Fischel, A. : hybrid Echinoid larvae,
| |
| 261.
| |
| | |
| — variability of Duck embryos, 71.
| |
| | |
| Fischel, H. : isolated blastomeres of
| |
| Ctenophora, 210, 211.
| |
| | |
| -— derangement of blastomeres in
| |
| Ctenophora, 211.
| |
| | |
| Fischer: artificial parthenogenesis,
| |
| 124. ’
| |
| Foot : polar rings in Allolobophom,
| |
| | |
| 251.
| |
| | |
| Garbowski : function of pigment
| |
| ring in Strongylocentrotus egg, 192.
| |
| — first furrow and sagittal plane in
| |
| | |
| Echinoids, 260.
| |
| | |
| — grafting of blastulae fragments of
| |
| Echinus, 202.
| |
| | |
| Gerassimow: size of nucleus and
| |
| cells in Spirogyra, 269.
| |
| | |
| Giacomini: need of oxygen for the
| |
| Chick, efiect of low atmospheric
| |
| pressure, 109, 110.
| |
| | |
| Giardina : difierentiation of chromatin in female cells of Dytiscus.
| |
| | |
| Godlewski : the respiration of the
| |
| Frog’s eg, 110, 112, 113.
| |
| | |
| -— heterogeneous cross-fertilization,
| |
| 262.
| |
| | |
| Graf : fusion of blastomeres, 56.
| |
| | |
| Greeley: artificial parthenogenesis
| |
| produced by cold, 108.
| |
| | |
| — low temperatures and absorption
| |
| of water, 108.
| |
| | |
| Grobben : Cetochilus, 22.
| |
| | |
| Groom : effect of fertilization in
| |
| Cirripedes, 250.
| |
| | |
| Gigiber: regeneration in Protozoa,
| |
| | |
| 54.
| |
| | |
| Gurwitsch : monstrosities produced
| |
| in Amphibian embryos by chemical
| |
| reagents, 120, 123.
| |
| | |
| Hacker : Cyclops, 22.
| |
| | |
| Haeckel: recapitulation, 16.
| |
| | |
| — development of fragments of
| |
| blastulao of Crystallodes, 181, note.
| |
| Hr;ller : preformation and epigenesis,
| |
| | |
| 5.
| |
| | |
| Harvey: epigenesis, 13.
| |
| | |
| — metamorphosis, 14.
| |
| | |
| Hecker: growth of the human embryo, 62, 63.
| |
| | |
| Hansen: growth of guinea-pig embryos, 62.
| |
| | |
| Herbst : potassium, sodium, and
| |
| lithium larvae of Echinoderms,
| |
| 136-140.
| |
| | |
| —- significance of monsters for origin
| |
| of variatiops, 141.
| |
| | |
| 317
| |
| | |
| Herbst : necessity of elements present
| |
| in sea-water for normal development of Echinoid larvae, 141 sqq.
| |
| | |
| —— separation of blastomeres of Seaurchins in calcium-free sea-water,
| |
| | |
| 45.
| |
| | |
| — stimuli in ontogeny, 20, 272, 273,
| |
| 285.
| |
| | |
| — formation of Arthropod blastederm oxygenotactic, 114.
| |
| | |
| —— arms of Plutous due to presence of
| |
| skeleton, 187, 138, 144, 149, 274, 275.
| |
| | |
| I-Ierl itzka, development of half-blastomeres of Newt, 173.
| |
| | |
| Hertwig, 0. : centrifugalized Frog’s
| |
| egg, 29, 87.
| |
| | |
| —- rules for nuclear and cell division,
| |
| 31, 32, 85.
| |
| | |
| — — confirmed by pressure experiments, 34-36.
| |
| | |
| — gravity and Echinoderm eggs, 78.
| |
| | |
| —— insemination of Frog's egg, 79.
| |
| | |
| — cardinal temperatures for Rana
| |
| | |
| fusca. and csculenta, 97.
| |
| | |
| — monstrosities produced by high
| |
| and by low temperatures, 99.
| |
| | |
| — temperature and rate of development, 100.
| |
| | |
| —— monstrosities produced in Amphibian embryos by sodium chloride,
| |
| 119, 135.
| |
| | |
| — first furrow and sagittal plane in
| |
| Frog's egg, 165.
| |
| | |
| — compressedeggs: disproof of qualitative nuclear division, 34—86, 168,
| |
| 169, 240.
| |
| | |
| — development of half-blastomere of
| |
| Frog’s egg, 169.
| |
| | |
| — mutual interactions of developing parts, 271, 285.
| |
| | |
| Hertwig, 0. and R. : fertilization
| |
| processes altered by heat and cold,
| |
| 107.
| |
| | |
| — — by alkaloids, 126 sqq., 263.
| |
| | |
| His: mechanical explanation of
| |
| development, 3.
| |
| | |
| —- germinal localization, 17, 158.
| |
| | |
| — the blastoderm oxygenoti-opic,114.
| |
| | |
| Hunter: artificial parthenogenesis
| |
| by concentrated sea-water, 124.
| |
| | |
| Iijima: spiral asters in Nephelis egg,
| |
| 40.
| |
| | |
| Jenkinson: pressure experiments on
| |
| eggs of Antedon, 37, note.
| |
| | |
| — abnormalities of Frog embryos
| |
| produced by various solutions not
| |
| due to increased osmotic pressure,
| |
| 120, 133-136.
| |
| 318
| |
| | |
| Jenkinson: plane of symmetry, first
| |
| furrow and sagittal plane in Frog's
| |
| egg, 165-168.
| |
| | |
| Jennings: fertilization spindle in
| |
| Asplanclma, 34.
| |
| | |
| Kaestner: cardinal temperature
| |
| points for the Hen‘s egg, 102.
| |
| | |
| — malformations due to low tem~
| |
| peratures, 104. '
| |
| | |
| Kant : teleology, 286-289, 292, 297.
| |
| | |
| Kastschenko: injuries to blastoporic
| |
| lip in Elasmobranchs, 178.
| |
| | |
| Kathariner: gravity and the gray
| |
| crescent of the Frog's egg, 86.
| |
| | |
| King : cause of differentiation of lens,
| |
| 276, 276.
| |
| | |
| Knowlton : sec Lillie and Knowlton.
| |
| | |
| Kolliker: 16.
| |
| | |
| Kopsch : first furrow and sagittal
| |
| plane in Frog's egg, 165, 168.
| |
| | |
| —— efl'ect of injuries to blastoporic lip,
| |
| 178.
| |
| | |
| Korschelt: fusion of ova in Ophryotmcha, 202.
| |
| | |
| — nucleus of egg-cell in Dyfiscus, 252. .
| |
| | |
| Kostanecki and Wierzejski: efi'ect of
| |
| fertilization in Physa, 250.
| |
| | |
| Kowalewsky: 16.
| |
| | |
| Kraus : the role of water
| |
| growth of plants, 58.
| |
| | |
| Lang : effect of fertilization in Polyclads, 250.
| |
| | |
| Leibnitz : preformation, 15.
| |
| | |
| Lewis: causes of formation of lens
| |
| and cornea, 275, 276.
| |
| Lillie and Knowlton: eflect of low
| |
| temperatures in Amphibia, 100.
| |
| — temperature and rate of development, 101.
| |
| | |
| Lillie: effects of salts on ciliary
| |
| movement, 135.
| |
| | |
| — ghysiologically balanced solutions,
| |
| 1 6.
| |
| | |
| in the
| |
| | |
| — toxicity and valency, 136.
| |
| | |
| Loeb : suppression of cell-division
| |
| in Echinoids and Fishes, 56, 117.
| |
| -— eflect of light in development, 94.
| |
| —the respiration of Otmolabrua and
| |
| | |
| Fundulua eggs, 111.
| |
| | |
| —— the respiration of the ova of
| |
| Echinoids, 112.
| |
| | |
| — function of oxygen in regeneration
| |
| of Tubular-ia head and other processes, 114, 278, 274.
| |
| | |
| -— efi'ect of hypertonic solutions on
| |
| Fundulus and Arbacia eggs, 117.
| |
| | |
| --exovates produced by dilute seawater, 118, 190, 194, 195.
| |
| | |
| INDEX or AUTHORS
| |
| | |
| Loeb: artificial parthenogenesis,
| |
| 121, 124.
| |
| | |
| —- etfect of potassium cyanide in prolonging life of ova, 131, 132.
| |
| | |
| — eflect of certain salts on Fundulus
| |
| embryos and on Plutei, 135.
| |
| | |
| — toxicity and antitoxicity functions
| |
| of valency, 186.
| |
| | |
| -— effect of alkalies, 151.
| |
| | |
| — effect of gravity on Anmmularia,
| |
| 272, 273.
| |
| | |
| -gégterogeneous cross-fertilization,
| |
| | |
| Lombardini : electric currents, 91.
| |
| | |
| Lyon : need of oxygen for the eggs of
| |
| Arbacia, 112.
| |
| | |
| — action of potassium cyanide, 132.
| |
| | |
| Malebranche : preformation, 15.
| |
| | |
| Malpighi: preformation, 14, 15.
| |
| | |
| Marcacci : mechanical agitation of
| |
| Hen's eggs, 90.
| |
| | |
| Mark: spiral asters in eggof Lz‘maac,40.
| |
| | |
| Mathews: artificial parthenogenesis
| |
| by mechanical agitation, 90.
| |
| | |
| —— effects of atropine and pilocarpine
| |
| on Echinoderm eggs, 131.
| |
| | |
| —toxicity and decomposition tension,
| |
| 136.
| |
| | |
| — see also Wilson (E.B.)and Mathews.
| |
| | |
| Mencl : formation of lensin SaImo,276.
| |
| | |
| Metsclinikoif : separation of blastemeres of Oceania, 181.
| |
| | |
| -—fusion of blastulae in Mitrocoma, 202.
| |
| | |
| Minot : rate of growth defined, 60.
| |
| | |
| —— change of rate of growth of guineapigs, 61.
| |
| | |
| — - of rabbits, 62, 68.
| |
| | |
| — — ofchickens, 67.
| |
| | |
| — coeflicients of growth, 65.
| |
| | |
| — senescence, 65.
| |
| | |
| -- increase of cytoplasm, decrease of
| |
| mitotic index, 65.
| |
| | |
| — change of variability in guineapigs, 71. _
| |
| — genetic restriction, 246, 277.
| |
| Mitrophanow: malformations due to
| |
| low and high temperatures, 104.
| |
| — necessity of oxygen for the Chick,
| |
| 109.
| |
| | |
| Moore : sodium sulphate an antidote
| |
| to sodium chloride, 135, 186.
| |
| | |
| Morgan : suppression of cell-division
| |
| in Arbacia, 56, 118.
| |
| | |
| - gravity and the gray crescent of
| |
| the Frog's egg, 86.
| |
| | |
| -— monstrosities produced by low
| |
| temperatures in Ranapaluslris, 100.
| |
| | |
| — need of oxygen for the Frog's egg,
| |
| 110.
| |
| INDEX OF AUTHORS
| |
| | |
| Morgan :lithium salts used to produce
| |
| alzlgéiormalities in Frog's eggs, 120,
| |
| | |
| — attempts to induce
| |
| parthenogenesis, 124.
| |
| | |
| — number of chromosomes in artificial parthenogenesis, 125.
| |
| | |
| — artificial parthenogenesis produced
| |
| by cold, 108.
| |
| — first furrow, plane of symmetry,
| |
| and sagittal plane in Frog's egg,
| |
| 165,168.
| |
| | |
| — development of half-blastomere of
| |
| | |
| Frpg's egg ; post-generation, 170,
| |
| | |
| 17 .
| |
| | |
| — development of vegetative cells of
| |
| Frog’s egg, 173.
| |
| | |
| — potentialities of half-blastomeres
| |
| in Teleostei, relation of flrstfurrow
| |
| tn sagittal plane, effect of removal
| |
| of yolk, 178.
| |
| | |
| — effect of injuries to blastoporic lip,
| |
| 179.
| |
| | |
| — number of cells in partial larvae
| |
| of Amphioxus, 181.
| |
| | |
| — potentialities of ectoderm in
| |
| Echinoids, 195.
| |
| | |
| — development of egg-fragments of
| |
| Echinoids, 197.
| |
| | |
| — number of cells in partial larvae
| |
| of Echinoids, 198.
| |
| | |
| — fusion of blastulae of Sphaerechinua,
| |
| 201.
| |
| | |
| — and Driesch: isolated blastomeres
| |
| and egg-fragments of Ctenophora,
| |
| 210-212.
| |
| | |
| — micromercs of Ctenophore egg, 30.
| |
| | |
| —- characters of hybrid Echinoid
| |
| larvae, 260.
| |
| | |
| Moscowski : gravity and the gray
| |
| crescent of the Frog's egg, 86.
| |
| | |
| Miihlmann : prenatal growth-rate
| |
| in man, 64.
| |
| | |
| artificial
| |
| | |
| Nfigeli : permutations of original
| |
| elements in development, 286.
| |
| | |
| Pander: 16.
| |
| | |
| Pearson : variability in man, 73.
| |
| | |
| Pfliiger: isotropy of the cytoplasm,
| |
| 18, 158.
| |
| | |
| —--influence oi’ gravity on development, 18, 78, 81-83, 168.
| |
| | |
| -- rule for direction of nuclear
| |
| division, 32, 85.
| |
| | |
| Plateau : principle of least surfaces,
| |
| 41, 43.
| |
| | |
| Platnerz 280.
| |
| | |
| Pott : growth of the Chick, 59, 60, 67.
| |
| | |
| 319
| |
| | |
| Pott and Preyer: respiration of the
| |
| Chick, 112.
| |
| — loss of weight of Hen’s egg due to
| |
| evaporation from albumen, 115.
| |
| Preyer : rate of growth, 60.
| |
| | |
| Quetelet: change of rate of
| |
| in man (weight), 68.
| |
| | |
| — — (stature), 69.
| |
| | |
| — — (other dimensions), 90.
| |
| | |
| growth
| |
| | |
| Rauber : efiect of reduced atmospheric pressure on the Frog’s egg,
| |
| 110.
| |
| | |
| — elfect of pure oxygen on the eggs
| |
| and tadpoles of the Frog, 118, 114.
| |
| | |
| Reichert: 16.
| |
| | |
| Remak : 16.
| |
| | |
| Robert : mechanics of spiral segmentation, 45-47.
| |
| | |
| — rate of growth in man, 68.
| |
| | |
| —-— change of variability, 73.
| |
| | |
| Rossi : efi‘ect of electricity on
| |
| Amphibian eggs, 91.
| |
| | |
| Roux : aims of experimental embryology, 13.
| |
| | |
| — ‘Mosaik-Theorie ’ of self-differentiation, 17, 158, 279, 286, 297.
| |
| | |
| — qualitative nuclear division abandoned, 19, 159, 240.
| |
| | |
| — idioplasm and reserve-idioplasm,
| |
| 159, 266.
| |
| | |
| — a half-embryo from one of first
| |
| two blastomeres and post-generation of missing half, 159, 162.
| |
| | |
| — coincidence of first furrow and
| |
| sagittal plane in Frog's egg, 17, 159,
| |
| 165. '
| |
| | |
| — the spermatozoon and symmetry
| |
| of the Frog's egg and embryo, 80,
| |
| 165, 247, 248.
| |
| | |
| — meaning of karyokinesis, 252.
| |
| | |
| — dependent diflerentiation, 17, 158,
| |
| 277, 286.
| |
| | |
| — functional adaptation, 290.
| |
| | |
| -— specific gravity of contents of
| |
| Frog’s eg, 79.
| |
| | |
| —- gray crescent of Frog's egg, 80, 165.
| |
| | |
| — influence of gravity on the Frog's
| |
| egg, 85-87.
| |
| | |
| — effect of electricity upon the Frog’s
| |
| egg, &c., 92.
| |
| | |
| — light and development, 93.
| |
| | |
| — segmentation of Rana esculenta, 26.
| |
| | |
| —- Frog's eggs compressed in small
| |
| tubes, 39, 40.
| |
| | |
| — comparison of systems of oil drops
| |
| and segmenting ova, 49-58.
| |
| | |
| — cytotropism, 55, 278.
| |
| 320
| |
| | |
| Roux: cytotaxis, 55.
| |
| | |
| — cytochorismus, 45.
| |
| | |
| -— cytarme, 45, 53.
| |
| | |
| — cytolisthesis, 58.
| |
| | |
| — ‘ Framboisia’, 135.
| |
| | |
| Ruseoni : electric currents, 91.
| |
| | |
| Sachs : law of direction of cell
| |
| division, 28.
| |
| | |
| Sala: fertilization processes altered
| |
| by cold, 108.
| |
| | |
| - fusion of the eggs of Ascaris, 202.
| |
| | |
| Samassa: effect of pure oxygen at
| |
| pressures on the Frog's egg,
| |
| | |
| — effect of lack of oxygen on the
| |
| Frog's egg, 119.
| |
| | |
| — effect of various gases on the eggs
| |
| of Ascaris, 112.
| |
| | |
| —development of animal cells of
| |
| Frog's egg, 173.
| |
| | |
| — Schaper: development of tadpoles
| |
| after removal of brain and eyes,
| |
| 175.
| |
| | |
| —- cause of differentiation of lens,
| |
| 275.
| |
| | |
| Schulze, F. E. :
| |
| Sponges, 22.
| |
| Schulze, 0.: gray crescent of Frog’s
| |
| | |
| eg, 80, 247.
| |
| | |
| —— gravity and the Frog’s egg, 86.
| |
| | |
| —- effect of low temperatures on the
| |
| Frog's egg, 100.
| |
| | |
| —— first furrow and sagittal plane in
| |
| Frog's egg, 165.
| |
| | |
| — double monsters from Frog’s egg,
| |
| 171.
| |
| | |
| Seeliger : hybrid Echinoderm larvae,
| |
| 260, 269.
| |
| | |
| Selenka: first furrow and sagittal
| |
| plane in Echinoids, 250.
| |
| | |
| Semper: rate of growth in Limnaea, 67.
| |
| | |
| Smith: Peltogaster, 24.
| |
| | |
| Sollmann : after effects of hypertonic
| |
| solutions, 124.
| |
| | |
| Spemann : development ofconstricted
| |
| Newt's eggs, and embryos, 174, 175.
| |
| | |
| — causes of formation of lens and
| |
| cornea, 275, 276.
| |
| | |
| Sumner: injuries to blastoporic lip
| |
| of Teleostei, 178, 246.
| |
| | |
| Sutton {individuality of chromosomes
| |
| in Brachyslola, 256.
| |
| | |
| Swammerdam : preformation, 14, 15.
| |
| | |
| segmentation of
| |
| | |
| Vejdovsky : unequal centrosomes in
| |
| dividing pole-cells, 31.
| |
| | |
| — polar rings in Rhym.-hclmis, 251.
| |
| | |
| Vernon: rate of growth in Strongmlocmtrotus, 67, 70.
| |
| | |
| INDEX or AUTHORS
| |
| | |
| Vernon : alteration of variability in
| |
| Echinoid larvae, 71, 74.
| |
| | |
| -— effect of light on Echinoid larvae,
| |
| 95, 96. '
| |
| | |
| — effects of change of temperature
| |
| on Echinoid larvae, 106, 107.
| |
| | |
| -— change of variability produced
| |
| by heat, 107.
| |
| | |
| — and by chemical agency, 141, 156.
| |
| | |
| —poisonousness of carbon dioxide
| |
| to Sea-urchin eggs, 112.
| |
| | |
| — characters of hybrid Echinoid
| |
| larvae, 261.
| |
| | |
| Verworn : behaviour of Protozoa in
| |
| an electric current, 93.
| |
| | |
| — regeneration in Protozoa, 254,
| |
| note.
| |
| | |
| Walter, sec Endres and Walter.
| |
| | |
| Weber : law of stimuli, 272.
| |
| | |
| Weismann: qualitative
| |
| division, 19, 297.
| |
| | |
| — idioplasm, and reserve—idioplasm,
| |
| 159.
| |
| | |
| Weldon : growth-rate in Carcinus, 71.
| |
| | |
| — change of variability in Carcinus,
| |
| 72.
| |
| | |
| — — in Clausilia, 73.
| |
| | |
| Wetzel : double monsters
| |
| Frog’s egg, 172, 245.
| |
| | |
| Whitman : polar rings in Clepsine,
| |
| 251.
| |
| | |
| Wierzejski, see
| |
| Wierzejski, 250.
| |
| | |
| Wilson, 0. B. : malformations of
| |
| Amphibian embryos, 120.
| |
| | |
| — acclimatizution to salt-solution,
| |
| 136.
| |
| | |
| Wilson, E. B. :
| |
| phioxus, 26.
| |
| | |
| —— segmentation of Renilla, 55, note.
| |
| | |
| — unequal centrosomes in dividing
| |
| pole-cells, 31.
| |
| | |
| —pressure experiments on eggs of
| |
| Nareis, 39, 213, 240.
| |
| | |
| - cytology of artificial parthenogenesis, 124.
| |
| | |
| — development of isolated blastemeres in Amphioxus, 179, 180.
| |
| | |
| —— isolated blastomeres of Oerebratulus,
| |
| and fragments of blastulae, 205,
| |
| 206.
| |
| | |
| — isolated blastomeres of Patella,
| |
| 218-222.
| |
| | |
| —- of Dentalium, 225, 226.
| |
| | |
| —— removal of polar lobe, 224.
| |
| | |
| — effect of fertilization, 222, 223.
| |
| | |
| — development of egg-fragments,
| |
| 226, 227.
| |
| | |
| nuclear
| |
| | |
| from
| |
| | |
| Kostanecki and segmentation of Am
| |
| | |
| Wilson (E. B.) and Mathews : spermpath, egg axis, fix-st furrow, and
| |
| embryonic axes of Toacopneustes,
| |
| 185, 249, 250. ‘
| |
| | |
| Windle: effect of magnetism and
| |
| electricity on development, 91.
| |
| | |
| Wolff : epigenesis, 16. '
| |
| | |
| Yatgu: egg-fragments of Cerebratulus,
| |
| | |
| 2 7.
| |
| | |
| Yung: effect of light on tadpoles,
| |
| etc., 94.
| |
| | |
| Zeleny : egg-fragments of Cerebratulus,
| |
| 206, 207.
| |
| | |
| Zelinka : fertilization
| |
| Callidma, 34.
| |
| | |
| spindle in
| |
| | |
| Jnxntsonr’ Y
| |
| | |
| Ziegler : heterodynamic centrosomes, 80.
| |
| | |
| .— formation of micromeres in Cteno
| |
| phora, 209, note.
| |
| | |
| -— pressure experiments on egg
| |
| gaéiinoids and Ctenophora,
| |
| | |
| — fertilization of Diplogaster, 84.
| |
| | |
| — egg and embryonic axes, 250.
| |
| | |
| Zoja : isolated blastomeres of Hydromedusae, 181, 182.
| |
| | |
| —— animal and vegetative cells of
| |
| Strongylocentrotus, 198.
| |
| | |
| Zur Strassen : segmentation of
| |
| Asoaiis, 81.
| |
|
| |
|
| — fusion of the eggs of Ascaris.
| | Index of Authors |
|
| |
|
| s of
| | Addenda |
| 88,
| |
|
| |
|
| ==Addenda Et Corrigenda== | | ==Addenda Et Corrigenda== |
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