Paper - On the relative growth of the component parts and systems of the albino rat (1912)

From Embryology
Embryology - 27 Sep 2020    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Jackson CM. and Lowrey LG. On the relative growth of the component parts (head, trunk and extremities) and systems (skin, skeleton, musculature and viscera) of the albino rat. (1912) Anat. Rec. 8(12): 449-474.

Online Editor 
Mark Hill.jpg
This historic 1912 paper by Jackson and Lowrey describes relative growth of the component parts and systems of the albino rat.



Modern Notes: rat

Rat Links: rat | Rat Stages | Rat Timeline | Category:Rat
Historic Embryology - Rat 
1915 Normal Albino Rat | 1915 Abnormal Albino Rat | 1915 Albino Rat Development | 1921 Somitogenesis | 1925 Neural Folds and Cranial Ganglia | 1933 Vaginal smear | 1938 Heart



Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

On the Relative Growth of the Component Parts (head, trunk and extremities) and Systems (skin, skeleton, musculature and viscera) of the Albino Rat

C. M. Jackson and L. G. Lowrey

From the Anatomical Laboratory of the Unirersity of Missouri

Two Figures

Introduction

To comprehend fully the growth of the body, the following data are reqmred: (1) the growth of the body as a whole; then an analysis to determine (2) the growth of the principal parts; (3) the growth of the various systems; (4) the growth of the individual organs; and finally (5) the growth of the ultimate constituent tissues and cells. Observations upon these various phases of growth in different animals are scattered through the literature, but in no case are they sufficiently complete to afford a comprehensive view of the process of growth in any individual species. In the case of the albino rat, the growth of the body as a whole and of the central nervous system has been carefully studied by. Donaldson and his associates. The present paper will give a partial analysis of the growth process in this animal, including the relative growth from birth to maturity in the various constituent parts and systems of the body. A more extensive study of the growth and variation in the individual viscera will be published soon in a separate paper.


Material and Methods

Ninety-three albino or white rats (Mus norvegicus albinus) were utilized for the present paper. These include 18 newborn (9 males, 9 females) ; 19 at 1 week (8 m., 11 f.) ; 13 at 3 weeks (7 m., 6 f .) ; 14 at 6 weeks (6 m., 8 f .) ; 10 at 10 weeks (5 m., 5 f.) ; 13 at about 5 months (6 m, 7 f .) ;-and 6 at about 1 year (4 m., 2 f .) . They were fed daily with wheat bread soaked in whole milk, and a supply of chopped- corn was kept constantly in the cages. In addition, they were fed fresh meat (beef) once a week. They were well cared for in an animal house, and represent well-nourished, healthy animals. In a few of the older animals, the lungs were infected, but none is included in which the infection was apparently sufficient to affect the general nutrition or vigor.

The various litters were kept separate and are indicated in the tables. Wntiile the number of animals is not large (on account of the laborious method of dissection) , it is sufficient to give some idea of the average condition and of the extent of variation. Since the personal equation is likely to enter to a certain extent in the process of separating the muscular and skeletal sj^stems, etc., in dissection, those litters dissected by Lowrey are designated by the prefix A or M with the litter number. Those without prefix (including all the observations given for the head, trunk and extremities) were dissected by Jackson.

The method of dissection was as follows. The animal was taken in the morning before feeding and killed by chloroform. The gross body weight, and the lengths of body and tail were recorded. The head was then removed (just posterior to the foramen magnum and anterior to the larynx) and weighed. In the meantime, the trunk was suspended and the blood (unmeasured) was allowed to escape. Then the viscera were carefully removed and weighed individually (including brain, -spinal cord, e3'eballs, thyroid, thymus, heart, lungs, liver, spleen, stomach and intestines, both with contents and empty, suprarenals, kidneys and gonads. Urine was estimated if present. The extremities were separated at the shoulder and hip joints and weighed. The skin was next removed (including ears, claws and adherent subcutaneous tissue) and weighed. Then the musculature with skeleton was weighed, the few remaining additional structures (genitalia, large vessels, pharynx and oesophagus, larynx and trachea, and masses of fat connected with the musculature) having been carefully removed. Finally the musculature was carefully dissected off and the skeleton, including bones, cartilages and ligaments, was weighed. This weight, subtracted from that of the skoloton and niiisrulatiiro to{i;cthor, gives the weight of the inuscuhituie, inchuliug the teiulous. Evuporatioii was reduced to a luiiiimum by keeping the various structures in a closed moist container, so far as possible. The net body weight, which is the gross body weight minus contents of stomacli, intestines and urinary bladder, was used as the basis in calculating the percentage weights. The percentages are therefore slightly higher than they would be if calculated upon the gross body weight. The ditference is not of material importance in the case of the albino rat. however, as the contents do not average more than 5 per cent of the body at the ages observed (excepting at 6 weeks, where the average was about 8 per cent.

The observations were grouped at seven ages, chosen for the following reasons. At 1 week the weight at birth has about doubled. At 3 weeks, it has about doubled again, and this moreover is the age at which the animal is usually weaned. At 6 weeks, the body weight has again about doubled, and the animal is well established upon its permanent diet. Ten weeks represents the age of puberty, and the body weight of 6 weeks has again about doubled. At 1 year, the bod}' weight has again nearl} doubled, and this represents nearly the adult weight. Five months was arbitrarily selected as the time when the body weight is approximately half w^ay between those of 10 weeks and 1 year. While therefore observations are not available for the various intermediate age periods, these are sufficientlj close together so that no important change in the relative weights of the constituent parts is likely to be overlooked. Moreover, on account of the variations at the different ages in the body weights, these form a fairly continuous series; and the relative weights of the various constituent parts are apparently more closely correlated with the body weight than with the age.

Observations (by Jackson) upon 5 wild gray or brown rats (Mus norvegicus) are also included for comparison, in tables 5 and 6. These rats were captured by traps in barns, and were probably chiefly grain-fed.

For the sake of economy of space, and since the present paper is concerned primarily with the relative weights, the percentage weights only are recorded in the tables. The absolute weight of the' body (net) is given in all cases, however, from which the absolute weight of the individual parts can easily be calculated if desired. Moreover, the original data will be deposited in The Wistar Institute of Anatomy in Philadelphia, where they will be accessible to any who may care to use them.


Relative Growth of the Component Parts

1. Head (tables 1, 2, 5; fig. 1). In the limited series of data given in table 1, it will be noted that, on the average (table 2), the head increases from 21.65 per cent of the body in the newborn to 23.70 per cent at 1 week; decreasing to 20.22 per cent at 3 weeks, 11.80 per cent at 6 weeks, 9.56 per cent at 10 weeks, 9.42 per cent at 5 months, and 9.29 per cent at 1 year. In a much larger series, however, including 20 or more of each sex at each age (observed by Jackson in a study of the growth of organs), the relative weights were found to average somewhat higher, being 23.43 per cent, 25.74 per cent, 24.27 per cent, 15.17 per cent, 11.21 per cent, 10.47 per cent and 10.75 per cent, respectively (data in parentheses in table 2.) This is to be explained partly on account of individual variations in the smaller series, and partly as due to correlation with the body weight, which in all cases averages heavier in the smaller than in the larger series of corresponding age. In constructing the diagram in Fig. 1, the data from the larger series were used.

No difference in the relative weight of the head (aside from that due to different body weight) is evident between the sexes; and the small series of observations on the gray rat (table 5) shows the head to be of approximately the same relative size as in the albino.


Fig. 1 Change in the percentage weight of the component parts of the albino rat. The width in the vertical direction) of each strip is proportional to the percentage weight of the corresponding part. The percentage weight is indicated for every part at each of the ages. Up to the age of 10 weeks (that is, in the ruled portion of the figure), the horizontal distance is drawn to scale, proportional to the age. Beyond 10 weeks, the horizontal distance is not in proportion to the age.


TABLE 1 Albino rat— Percentage iveight of the head, trunk and extremities Newborn

LITTER NUMBER


SEX


NET BODY WEIGHT


HEAD


UPPER EXTREMITY


LOWER EXTREMITY


TRUNK


47


m.


grams

5.88


per cent

22.60


per cent

7.27


per cent

9.70


per cent

60.43


47


m.


5.96


22.40


7.57


8.49


61.54


47


m.


6.25


21.12


8.45


8.00


62.43


62


f.


4.27


21.08


7.07


9.62


62.23


58


f.


5.09


21.59


7.27


10.41


60.73


63


f.


4 78


21_. 13


6.69


10.46


61.72


m.

f.

f.


One week


49


m.


11.96


23.06


7.27


12.88


56.79


46


m.


14.95


21.92


9.23


12.44


56.41


59


m.


9.55


25.03


8.90


11.62


54.45


60


f.


9.63


24.68


8.00


11.22


56.10


49


f.


10.33


23.54


9.37


11.13


55.96


46


f.


13.23


23.98


10.74


12.55


52.73


Three weeks


53b


m.


25.80


19.49


7.40


15.20


57.91


53b


m.


29.08


18.97


10.94


15.37


54.72


53b


m.


29.89


18.24


9.50


14.27


57.99


57


f.


17.34


24.16


9.17


14.65


52.02


Six weeks


50a


m.


82.50


50a


f.


76.80


50a


f.


78.60


50a


f.'


78.80


11.25 12.15 11.82 11.97



Ten weeks


175.20 120.30 130.20


8.56

9.98

10.14


5.21 5.24 5.50


14.63 14.88 14.90 15.37


15.77 16.45 14.54


67.93 67.07 65.06 66.09


70.46 68.33 69.82



TABLE l-ContlMu.-.l Fire nionthfi^


UTTER NUMBER


SEX


NET BODY WEIOHT


HEAD

per cent

8.35

10.00

9.92


UPPKK EXTRKMITY


LOWER EXTREMITY


TRUNK


28 28 37


m. f. f.


grams

239.40 171.50 161.30


per cent 5.43 6.01 6.17


per cent 14.91 15.80 16.20


per cent

71.31 68.19 67.71


One year


39


m.


229.20


9.10


4.93


14.62


71.35


37


m.


276.40


9.18


4.67


14.54


71.61


39


f.


161.10


9.60


4.68


14.73


70.99


1 The third individual in this group was 8 months old.

TABLE 2

Albino rat — Average percentage weight of head, trunk and extremities at various

ages (from table 1 )


AGE


HEAD


1 UPPER

EXTREMITY

LOWER EXTREMITY


TRUNK



per cent


per cent


per cent


per cent


Newborn


21.65 (23.43)1


7.39


9.45


61.51 (59.73)'


One week


23.70 (25.74)


8.92


11.97


55.41 (53.37)


Three weeks


20.22 (24.27)


9.25


14.87


55.66 (51.61)


Six weeks


11.80 (15.17)


6.72


14.94


66.54 (63.17)


Ten weeks


9.56 (11.21)


5.32


15.59


69.53 (67.83)


Five months


9.42 (10.47)


5.87


15.64


69.07 (68.02)


One year


9.29 (10.75)


1 4.76


14.63


71.32 (69.86)


1 Figures in parentheses indicate the average percentages of the head (and corresponding percentages of the trunk) in a much larger series, including 20 or more of each sex at each age.


It is thus a remarkable fact that for a short time after birth the head of the albino rat grows more rapidly than the remainder of the body, probablj' reaching its maximum relative size in the second week. It is well known that the head of animals in general IS relatively largest during early embryonic life, and that it declines during the later prenatal period (cf. Jackson). After birth, since it is still relatively large as compared with the adult, the head would naturally be expected to continue to decline in


TABLE 3

Albino rat — Percentage weight of skin, skeleton, musculature and viscera

Newborn


LITTER NUMBER


SE^


NET BODY WEIGHT


SKIN


SKELETON


MUSCULATURE


VISCERA


REMAINDER


47


m.


grams

5.88


per cent

18.30


per cent

13.95


per cent 21.26


per cent

17.38


per cent

29.11


47


m.


5.96


16.90


15.61


22.56


19.00


25.93


47


m.


6.25


20.29


15.84


24.66


17.78


21.43


A22


m.


4.87


21.50


19.70


23.40


15.94


19.46


A23


m.


5.22


19.60


19.50


18.90


17.50


24.50


A24


m.


4.57


22.30


23.50


20.60


18.50


15.10


A34


m.


4.20


18.15


13.70


26.70


18.13


23.32


A34


m.


4.53


18.00


14.70


26.35


16.68


24.27


A34


m.


4.54


21.24


16.59


25.25


17.10


19.82


62



4.27


19.01


16.43


25.00


18.48


21.08


58



5.09


20.43


14.33


26.54


■ 18.21


20.49


63



4.78


19.46


16.50


27.85


19.68


1€\ 51


A25



4.44


21.00


20.40


21.30


20.17


17.15,


A29



3.58


21.20


24.80


23.90


19.86


10.24 ■<


A34



4.47


19.80


14.80


29.80


17.13


18.47


A34



4.17


17.65


15.74


24.42


18.17


24.02


A34



3.38


20.25


18.00


24.62


17.15


19.98


A34



4.26


20.37


16.80


25.60


18.02


19.21


One week


46


m.


14.95


29.36


15.78


22.41


17.43


15.02


49


m.


11.96


31.52


17.06


24.58


15.29


11.55


59


m.


9.55


25.23


17.49


24.60


19.68


13.00


A22


m.


10.30


29.90


22.20


22.50


19.92


5.48


A32


m.


8.99


23.96


17.70


22.53


18.61


17.20


A32


m.


10.76


25.45


18.90


19.25


20.13


16.27


M9


m.


8.11


24.10


19.40


23.70


20.98


11.82


M9


m.


9.12


23.50


18.60


23.50


20.42


13.98


46



13.23


29.37


14.36


24.35


18.26


13.66


49



10.33


31.75


15.30


26.52


15.55


10.88


60



9.63


25.34


17.54


24.00


18.55


14.87


A21



8.85


28.60


23.80


23.40


18.41


5.79


A24



7.65


24.20


23.60


19.00


20.63


12.57


A28



6.98


23.30


22.20


22.40


20.50


11.60


A32



8.76


21.30


16.10


19.60


19.80


23.20


A32



10.63


27.00


18.05


21.63


19.16


14.16


A33


I

8.07


21.78


18.52


22.47


20.09


17.14


A33



7.43


22.05


17.60


23.30


20.37


10.68


A33



9.95


23.96


16.70


23.90


20.46


14.98


GROWTH OF TIIK ALHINO ItAT


457


UTTER NTMUEH


5;ib 53b 53b

A32

M9

I\I9

M9

57 A26 A32 A32 A33 A33


50a A24 A24 A28 A29 A29

50a 50a 50a

A29

A29

A29

A31

A31


111. m. m. m. m. m. 111.

f. f. f. f. f. f.


NET BODV WEIGHT

grams

25.80 29.08 29.89 25.91 25.78 25.40 26.50

17.34 18.41 23.72 25.70 24.40 24.30


TABLE 3-Contlmu'.|

Three weeks

BKI.V SKELBTON


per cent 29.20 26.39 27.49 18.70 22.10 21.50 19.50

22.26 23.55 21 . 10 19.80 18.80 20.55


per cent 14.90

16.72 13.11 17.30 15.70 15.60 15.80

19.49 21.08 16.65 17.10 15.90 16.43


MU8CULATURB


per cent 29.80 28.08 27.69 27.10 26.70 26.30 28.30

30.22 20.14 25.66 27.50 25.30 26.77


24.82 20.57 21.90 20.91 20.09 20.35


Six weeks


m. m. m. m. m. m.

f. f. f. f. f. f.


82.5 54.1 41.5 56.6 62.9 62.9

76.8 78.6 78.8 54.7 59.8 64.8 64.7 62.7


25.86 20.00 20.20 19.80 17.90 17.63

25.53 24.94 25.55 16.74 21.00 19.10 19.70 18.84


11.67 15.15 20.10 14.70 14.16 14.31

10.50 12.63 11.82 14.13 13.60 13.40 14.15 15.35


35.13 29.60 26.10 33.70 34.90 34.45

28.56 33.77 35.25 33.82 34.60 33.90 31.42 32.60


20.80 20.37 21.79

20.78 21.47 22.89

18.35 19.22 18.41 21.27 19.98 19.72 20.41 20.01


I<GMAI.NI>KR


per cent


jyer cent


22.08


4.02


21.59


7.22


20.38


11.33


20.79


10.11


20.61


14.89


20.24


10.30


22.35


14.05


Ten weeks


3.21 14.66 14.69 14.69 19.91 15.90


6.54 14.88 11.81 11.02 11.57 10.72

17.06 9.44 8.97 14.04 10.92 13.88 14.32 13.20


50b


m.


175.2


20.95


11.07


43.15


16.15


8.68


A28


m.


109.2


1 15.60


12.00


39.60


17.57


15.23


A 28


m.


134.3


16.80


10.40


40.90


16.69


15.21


A30


m.


144.7


t 18.70


12.20


37.40


15.72


15.98


A30


m.


187.2


18.80


10.00


37.90


14.89


18.41


458


C, M. JACKSON AND L. G. LOWREY


TABLE 3— Continued

Ten weeks — Continued


LITTER NUMBER


SEX


NET BODY WEIGHT


SKIN


SKELETON


MUSCULATURE


VISCERA


REMAINDER




grams


per cent


per cent


per cent


per cent


per cent


50b



120.3


22.28


12.39


49.13


14.97


1.23


50b



130.2


21.34


12.90


41.78


15.75


8.23


A26



109.9


17.93


11.70


41.42


16.32


12.63


A28



108.4


16.70


12.20


42.30


14.99


13.81


A29



122.2


17.80


11.90


37.80


17.22


15.28


Five months^


28


m.


239.4


22.76


13.24


41.39


15.39


7.22


A22


m.


192.3


18.80


12.30


42.10


12.99


13.81


A26


m.


203.4


18.50


10.40


43.90


13.26


13.94


A26


m.


232.4


18.90


10.00


43.10


13.42


14.58


A26


m.


195.4


18.30


10.20


41.20


14.02


16.28


A26


m.


249.4


18.00


9.37


44.30


13.13


15.20


37


f.


161.3


20.36


10.54


46.50


12.53


10.07


28 f.


171.5


17.79


14.58


46.25


14.53


6.85


A22 f.


157.1


18.80


11.60


40.20


16.19


13.21


A22 f.


158.0


16.20


12.20


39.70


15.46


16.44


A22


f.


158.5


15.70


10.90


41.90


17.24


14.26


A22


f.


128.2


14.50


11.80


41.90


18.70


13.1.0


A26


f.


149.0


17.20


12.90


41.90


15.21


12.79





One


year'^





39


m.


229.2


15.93


9.69


46.51


14.86


13.01


37


m.


276.4


20.62


11.61


42.65


13.63


11.49


A—


m.


253.5


18.45


10.45


46.33


11.49


13.28


A—


m.


281.6


13.75


7.35


50.50


12.17


16.23


39


f.


161.1


21.97


10.86


41.15


13.85


12.17


3


f.


206.0


16.99


15.53


45.46


13.82


8.20


1 The first female of the 5 months' list was 8 months old. The age of the third and fourth males of the year list was not exactly known, but it was in the neighborhood of a year.


relative size, imd we meet no data or statements to the contrary in the Hterature. \\'hether this early postnatal acceleration of the head growth is peculiar to the rat is therefore unknown, as well as its relations to prenatal f2;rowtli.

It is interesting to note that the maximum relative weight of the head of the young rat (about 26 per cent) is nearly the same as that observed by Jackson for the human newborn; and that the adult rat head (9 to 10 per cent) is also not far from that of the human (6 to 10 per cent) as given by Meeh and Harless. Few data are available for comparison with other forms. Martiny, in 3 groups of beef cattle (10 in each group), finds the head forming an average of 2.7 per cent to 2.9 per cent of the body weight. Lawes and Gilbert give data showing the head in 2 fat calves to average 5.5 per cent of the body weight; and in 16 adult heifers and steers, 2.7 per cent. In 249 sheep they find the head averages 2.9 per cent of the body, varying from 3.6 per cent in 5 thin yearlings to 2.5 per cent in 45 very fat sheep, aged If years. Lowrey finds that in the pig the head decreases from about 22.3 per cent (late fetus) to an average of 6.3 per cent in the adult.

2. Extremities (tables 1, 2, 5; fig. 1). In spite of individual variations shown in table 1, the upper extremities on the average (table 2, fig. 1) are seen to increase from 7.39 per cent of the body at birth to 8.92 per cent at 1 week, and to 9.25 per cent at 3 weeks. From this maximum relative size, they decrease rapidly to 6.72 per cent at 6 w^eeks, and thereafter more slowly to an average of 4.76 per cent at 1 year.

The lower extremities show a continuous relative increase, w^hich is at first more rapid, from an average of 9.45 per cent at birth to 11.97 per cent at 1 week, and to 14.87 per cent at 3 weeks. Thereafter the increase is slower, reaching a maximum of 15.64 per cent at 5 months, with an apparent later slight decrease to 14.63 per cent at 1 year.

The number of observations is insufficient to show any difference between the sexes as to relative weight of the extremities, if such exists. Similarly, the data on the gray rat (table 5) reveal no significant difference from the albino.



u^ t^


■* ■*


O "*


CT> CO


o CO


^ s


o a>



lO lO


O 1-H


o 00


O t-

t^ (N


lo CO


lO 1—1


« ■


c^i 00


CO '^


(m' CO


rt (>■!


'*' d


CO (m'


CO d


<M ^


1—1 T— 1


,— 1 r-l


T' T'


»— 1 "—I


1 1


1 1


Q


s 1. 1


1 1


1 1


1 1


1 1




g

s


- s ^


ij^


Bj^


a ^


a ^


a^


a u;






H


^ o


00


lO


CO


r—


T-H


o


K


lO


o


00


o


•*


Oi


•^



o


CO


ci


(M


c^i


c<i


'M



<M .



^^


'"'


'"'


T-l


'^



CO •*


CO lO


»o '^


lO t^


O lO


O 03


^ -*



»0 lO


O (M


^ ^^


CO CO


<M 00


t^ CO


o 00



i^ 00


o o


,— i ^


— 1 Ol


d iQ


CO lO


CO CO





(M <M


(M T-H





<


■" 1 1


1 1


1 1


1 1


1 1


1 1


1 1


m


8 '. '


s ^


s ^


a ^


a ^


a ^


a <^


s









>


a |_


t^


00


o


CO


t^


o



o



(M


CO


o


i^


CO



00


oi

^


d


d


TtH


CO




.— 1


(N


(M


'"'


'"'


^"^



o »c


00 00


r-l CO


r-l 05


CJ 03


CO (M


9 "^^



CO 'f


00 t^


!>. C3


CO C5


l-^ ■*


CD CD


lO CO


a


CO lo


(M ■>!


l>. lO


(m' c^j


d <M


<N (N


d CO



C^ (M


(N <M


<M (M

1 1


CO CO


7 T


1 1


T T ■


fn


S '. '




,





.-1


s B ^


-i^


B ^


a ^


Bj^


a ^


a u^


g




"^ — V. — '




"■ — ^- — '


^ — ^ — '


QO


^ t^


(M


OS


o


-*


■*


CO


P


CO


00


00


t^


"— J


CO


•*



•^


C-1


r-^


oi


,—1


oj


12



(M


(M


(M


CO


'^


'i**


-*



1—1 CO


Ol 05


Oi 00


(M O


CO (M


(M t

00 02



O lO


CO »o


lo r

O (M


1— 1 C^


03 O


t^ ^



t— t~

00 00


lO t^


lO CO


rH (M


d (>i


Oi CO


z





T-H T— 1


i-H T-H


T-H T-H


T— H


o


"S^ '^


1 1


i_ 1


1 1


1 1


1 1


1 1


i-1


2 S u^


i5


s ^


Bj^


a ^


a ^


a ^


^ t

t^


"^"^


GO


t^


M^


^


CM


'^i


CO


02


o


lO


03



t^


00


COS


CO



^


d

r-H



CI »— 1


CO CO


>0 -H


CO (M


t^ 1-H


T-H C^


03 00



lO 05


CO CO


lO o


C^ Tfi


--H C^


C^ (M


-H -ct*



o^ o


CO lO


CO ^


O '-I


CO Oi


05 t-

t^ CI



't— ( 1— 1 '*^ t 1


7 7


7 7


7 7


l_ 1


T 1*


V T


g (0



Sj^


i^


Bj»



Bj^


^^


^^~^


00


00


,_,


C3


^


lO



t^


00


CO


Ci


CD


"-*


o



03


lO


(M


d


00


00


t^




(M


c^


(M


^"^


'"^


i-H


•<


r^' .


a ^"


a .«•


a ^


a ^


a.*;


■^ o5



c5 oi


00 i-H


1^ CD


CD 00


lO lO


CO t^





pa 10


00


Oi


CO


-#


o


CO


o


D


"*

'"'


^~*


^~~'





z














Cfl






02









^






xi





c


^



CO


72


fi


^


<<



o



<u


o


a



S


0)



a;



a

0)




a;


G


^


X


OJ


r*


C



^



C



H


i/


5


h



fa


c



(iltOWni OK THE ALHINO 1{AT


461


Seurcely any data are found in the literature as a basis for comparison with other forms. The observations made upon domestic animals at the various agricultural experiment stations usually follow the 'butcher's cuts/ which unfortunately do not correspond to the anatomical subdivisions. The only data available are the observations by Jackson, Meeh and Harless (1. c), which indicate that in the human newborn the upper extremities form about 10 per cent of the body, which is about the same as in the adult; and that the lower extremities form about 20 per cent in the newborn and about 35 per cent in the adult. Thus, as might be expected, the extremities, especially the lower, are relatively much larger in man than in the rat. No observations are recorded for stages between the newborn and the adult.




TABLE 5




Gray (brown) rat — Percentage weight of head,


trunk and extremities


SEX


NET BODY WEIGHT


„_, . „ UPPER °^^° EXTREMITY


LOWER EXTREMITY


TRUNK


m.


grams

65.0


per cent per cent

14.66 5.95


per cent

13.88


per cent

65.51


m.


95.4


12.17 5.83


15.34


66.66


f.


107.5


10.18 j 5.58


15.81


68.43


m.


164.0


9.27 5.24


14.94


70.55


f.


254.01


7.85 5.02


13.68


73.45


1 Including gravid uterus, which weighed 13.76 grams.

3. Trunk (tables 1, 2, 5; fig. 1). The trunk weight w^as estimated by subtracting the weight of the head and extremities from the net body weight. The loss of blood (which was usually comparatively small) therefore falls entirely to the trunk. In the parentheses in table 2 are given the figures for the trunk corresponding to the larger series, as explained for the head, and these are also utilized for the diagram in figure 1. It is evident that both sets agree in showing that the trunk decreases notably in relative size from about 60 per cent of the body at birth to a minimum (52 to 55 per cent) at the first to third weeks (corresponding to the relative increase of the head and extremities), and thereafter increases steadily, reaching its maximum relative size (about 70 per cent) in the oldest and largest animals observed.


462 C. M. JACKSON AND L, G. LOWREY

No differences are evident on comparing the sexes, or the data for the gray rat (table 5) . The only data found in the literature for comparison with other forms are again those of Jackson and IVIeeh (1. c), which show that the trunk forms about 45 per cent of the body in the human newborn, and about 48 per cent in the adult. Thus the human trunk is relatively smaller, corresponding to the relatively larger extremities.

As Jackson has pointed out for the human body, it may likewise be noted in the rat that the intensity of growth seems to pass over the body somewhat like a wave, reaching its maximum first in the head and upper extremity, and later passing backward along the trunk to the abdominal portion and lower extremity. This relation is evident in figure 1. It is furthermore evident from this figure that the adult relations of the component parts of the body have practically been reached at 10 weeks. The only changes apparent thereafter are a very slight relative increase in the trunk, compensated by a corresponding decrease in the head and extremities.

RELATIVE GROWTH OF THE VARIOUS SYSTEMS

1. Skin (tables 3, 4, 6; fig, 2). As shown by table 4 and in figure 2, the integument (including claws and adherent subcutaneous tissue) grows with remarkable rapidity during the first week, the average increasing from 19.75 per cent to 25.88 per cent of the whole body. The numbers at each age are too large and the uniformity too great to account for this on the score of possible individual variations. This unquestionable increase is however somewhat difficult to explain. It is not due to the development of the hair coat, for this does not become well developed until the second and third weeks. Neither is it apparently due to any unusual accumulation of fat in the subcutaneous tissue.

Fig. 2 Change in the percentage weight of the various systems of the albino rat. The width (in the vertical direction) of each strip is proportional to the percentage weight of the corresponding system. The percentage weight is indicated for every system at each of the ages. Up to the age of 10 weeks (that is, in the ruled portion of the figure), the horizontal distance is drawn to scale, jjroportional tf) the age. Beyond 10 weeks, the horizontal distance is not in proportion to the age.



463


464


C. M. JACKSON AND L. G. LOWREY


After the first week the skin decreases in relative weight, at first more rapidly, and later more slowly, reaching an average of a little less than 18 per cent at 1 year. There are no noteworthy differences apparent between the sexes, or in the gray rat (table 6) ,

Numerous observations upon the integument in other forms are available for comparison, though chiefly for the adult. According to Vierordt, the average for the human newborn is 19.7 per cent; for the adult, 17.8 per cent. Welcker and Brandt record observations upon a large number of species, including besides mammals many birds (14 to 28 per cent), reptiles (6 to


TABLE 6

Gray {brown) rat — Percentage weight of skin, skeleton, musculature, viscera and

remainder


SEX


NET BODY WEIGHT


SKIN


SKELETON


MDSCaLATURE


VISCERA


REMAINDER



groTns


per cent


per cent


per cent


per cent


per cent


m.


65.0


18.42


13.15


35.39


23.40


9.64


m.


95.4


19.29


13.85


38.57


23.21


5.08


f.


107.5


20.37


13.86


42.14


17.51


6.12


m.


164.0


17.35


13.29


41.66


20.95


6.75


f.


254.01


19.41


10.16


44.21


16.22


10.00


1 Including gravid uterus, which weighed 13.76 grams.

21 per cent), amphibia (13 to 21 per cent), and fishes (5 to 13 per cent). These differ so widely in the structure of the integument (especially the appendages), however, that their relative weights are scarcely comparable with each other or with those of mammals. This is also true to a certain extent even for the various mammals. Of mammals, Welcker and Brandt give data for the relative weight of the integument as follows : shrew mouse (Sorex), young, 33.3 per cent, adult, 14 per cent; mouse, 17.6 per cent; bat, 19.5 per cent; mole, 20.2 per cent; hedgehog, 24.3 per cent; guinea pig, 19.8 per cent; monkey, 10.4 per cent; seal, 19.6 per cent; elephant, 13.1 per cent. Sedlmair finds the skin of a well-nourished cat forms 14.7 per cent of the body weight; and Weiske, for rabbits, 14.3 to 16.2 per cent. For dogs (Dachshund), Falck finds the average in 4 newborn 21.8 per cent; at 72 days, 25.4 per cent; 70 days, 18.8 per cent; 108 dnj^s, 10. G per eent; 113 days, 21.3 per cent.

For cattle and sheep numerous data are available. Lawes and Gilbert for 2 fat calves (9 to 10 weeks) find the hide averages 0.9 per cent of the bodj weight; for 16 adult cattle, 7.5 per cent. JMartinj' in 3 groups (10 each) of beef cattle found the average 7.8 per cent, 9.1 per cent and 8.0 per cent, respectively. For sheep. Lawes and Gilbert find in a fat lamb (6 months), the integument forms 9.6 per cent (skin proper, 5.9 per cent, wool, 3.7 per cent) ; in adults, the average of 249 sheep was 11.7 per cent, ranging from 14.1 per cent (in 5 thin yearlings) to 10.5 per cent (45 very fat adults, If years). Henneberg in 19 sheep finds the skin forming 7.1 per cent to 12.5 per cent. Long in 2 fat sows finds the skin (without fat) to form 4.9 per cent and 5.1 per cent.

The foregoing data are reckoned in percentage of the net body weight, excluding contents of the alimentary canal. Voit has pointed out further that if the state of bodily nutrition, the amount of fat and hair, etc., present are taken into account, the variations in percentage weight of the body for the different organs are much less. Thus in 6 dogs, the skin varied from 8 per cent to 19 per cent of the body weight; but reckoned on the fat-free, hair-free basis, the variation was only from 7 per cent to 9 per cent for the well-nourished, and from 7 per cent to 13 per cent for the poorly-nourished animals.

The relative weight of the skin in the rat is thus high as compared with that of most mammals. In general, the skin evidently forms a relatively larger percentage of the body weight in small animals, which is to be expected, since in these the surface area is larger in proportion to the mass of the body.

Skeleton (tables 3, 4, 6; fig. 2). The skeleton (including bones, cartilages and ligaments) like the skin, apparently increases relatively for a short time after birth, the average percentage being 17.27 per cent at birth, and 18.47 per cent at 1 week (table 4, fig. 2). Thereafter it diminishes steadily at the various ages studied, reaching an average of 10.91 per cent at 1 year. The high figure for one of the females at 1 year (15.53 per cent) is probably either an error or an abnormality. There are no constant differences apparent between the sexes, and the hmited data for the grayrat (table 6) are well within the limits of variation for the albino.

Of data available for comparison with other forms, Vierordt estimates the skeleton in the human newborn at 13.7 per cent; in the adult, 17.5 per cent. Miihlmann estimated that the human skeleton increases from 12.6 per cent in the newborn to a maximum of 20.4 per cent at 11 to 20 years, thereafter decreasing to 10.1 per cent in old age.

Welcker and Brandt in addition to numerous data for the skeleton of birds (7 to 13 per cent), reptiles (7 to 43 per cent), amphibia (7 to 10 per cent), and fishes (6 to 17 per cent), give the following for mammals: mouse, 8.4 per cent; bat, 14.6 per cent; hedgehog, 11.1 per cent; guinea pig, 8.8 per cent; seal, 11.1 per cent; monkey, 16.8 per cent; elephant (skeleton plus musculature), 69.7 per cent. Falck for Dachshund, newborn (average of 4), 14.4 per cent; nearly grown, 14.9 per cent; adult, 14.0 per cent. Sedlmair, for well-nourished cat, finds 10.1 per cent; Weiske, for rabbits, 8.1 per cent to 9.2 per cent.

Martiny, in 3 groups (10 each) of beef cattle, finds the skeleton averages 14. 3 per cent, 14.6per cent and 15.3per cent, respectively. Henneberg gives average of 2 lambs, 10.4 per cent; and of 8 adult sheep, 4.4 per cent to 7.1 per cent, being least in the fattest animals. Long, for 2 fat sows, gives 6.3 per cent and 6.7 per cent.

An inspection of the data given above shows great variation in the relative weight of the skeleton, even in animals close together in size and relationship. This is due partly to differences in skeletal structure and in the amount of musculature (with which the skeletal system is to a certain extent correlated) and partly to variation in the state of bodily nutrition. Voit shows, for instance, that among dogs whose skeleton varied from 12 per cent to 29 per cent of the body weight (as ordinarily reckoned) , if reckoned upon a fat-free, hair-free basis the percentage weight varies from 14 per cent to 15 per cent in well-nourished, and from 17 per cent to 30 per cent in poorly-nourished animals.

Musculature (tables 3, 4, 6; fig. 2). Unlike the skin and skeleton, the musculature (including tendons) appears to decrease slightl}^ in relative weight, from an average of 24.37 per cent to 22. (S2 por cent during the first week (table 4, fig. 2). Thereufter it iuereiises steadily in relative weight, reaching an average of 45.43 per cent at 1 year. No noteworthy difierences api)ear between the sexes, or in the gray rat (table 6).

The musculature forms so large a mass that its growth virtually dominates the bod}'. Thus during the first week, when the musculature lags behind in growth, the other constituents push ahead and increase their relative weights. Later, however, when the musculature assumes its characteristic more rapid rate of growth, it forges ahead and the other constituents necessarily decrease steadily in relative weight up to the adult condition. The increase in the relative proportion of the musculature between the newborn and the adult is also characteristic. of man, and perhaps to a shghter extent in other animals. No data are available to show whether there is in any other species a temporary decrease after birth as shown above for the rat. .

For the human newborn, Welcker and Brandt cite 2 cases from BischofT in which the musculature formed 23.3 per cent and 24 per cent of the body. Vierordt estimates for the human newborn, average, 25 per cent, and for the adult, 43.2 per cent. Miihlmann for newborn estimates 22.4 per cent, increasing to 43.2 per cent at 41 to 50 years, thereafter decreasing to 18.6 per cent in old age.

Welcker and Brandt, in addition to numerous birds (36 to 55 per cent), reptiles (19 to 57 per cent), amphibia (43 to 54 per cent), and fishes (49 to 59 per cent), give the following for the musculature of mammals: bat, 41.6 per cent; mouse, 43.4 per cent; hedgehog, 36.6 per cent; guinea pig, 45.8 per cent; monkey, 53.5 per cent; elephant (skeleton plus musculature), 69.7 per cent; ox (skeleton plus musculature), 64 per cent; deducting 15 per cent for skeleton (Martiny) gives 49 per cent. Falck, for Dachshund, finds in newborn, average, 36.2 per cent; nearly grown, 38.4 per cent; adult, 39.6 per cent. Sedlmair, for cat, finds 57.2 per cent; and Weiske, for rabbits, 49.7 to 57.2 per cent. Lawes and Gilbert, in a lean pig, find 41.6 per cent for muscle, and in a fat pig, 30.9 per cent. Long, in 2 fat sows, finds 29.7 per cent and 32.6 per cent. Henneberg, in 2 lambs, finds the average 34.4 percent ; in 8 adults, 20.3 per cent to 33.2 per cent, the lower percentage corresponding to the fatter animals.

Voit, in the 6 dogs previously mentioned, finds the musculature forming 36 per cent to 49 per cent of the body weight. Reckoned on a fat-free, hair-free basis, however, the variation is only 52 to 55 per cent for well-nourished, and 40 to 48 per cent for poorlynourished animals.

Thus in comparison with other animals with respect to the relative weight of the musculature, the rat occupies an intermediate position. In most adult mammals, the musculature forms between 40 per cent and 50 per cent of the body weight. Theoretically^, as Welcker has noted, a larger relative weight of muscle might be expected in a larger animal. This is because the functional capacity (tension strength) of a muscle varies as the crosssectional area, which would increase only in proportion to the square of a li^iear dimension, while the mass of the body to be supported and moved would increase as the cube of the same dimension. The data do not seem to confirm this theory, however. For example, the percentage of muscle is nearly the same in the mouse as in the elephant. Among mammals, the largest percentages of muscle recorded are in comparatively small animals (rabbit, cat), while the smallest relative weights are found in comparatively large animals (pig, sheep).

4. Viscera (tables 3, 4, 6; fig. 2). Like the skin and skeleton, the visceral group (including the central nerv^ous system, thoracic and abdominal viscera) increases in relative weight immediately after birth. In the newborn, it averages 18.05 per cent, increasing to 19.17 per cent at 1 week, and continuing to increase to a maximum of 21.28 per cent average at 3 weeks. Thereafter it diminishes gradually in relative weight, reaching an average of 13.3 per cent at 1 year. There are no evident differences between the sexes. The data for the gray rat (table 6) appear constantly higher than those for the albino of corresponding body weight. Whether this is really a constant difference is somewhat doubtful, however, on account of the small number of observations on the gray rat.


The visceral jj;r()up in the Iuuikui lunvboni averages about 24 per cent of the body weight (Jackson). According to Vierordt, it forms 23.4 per cent in tlie newborn, decreasing to 9.8 per cent in the adult. Accurate data for comparison of the intermediate stages are not available for man or for any other animal. In the pig, Lowrey finds about 16 ])er cent for the newborn, and 7.8 per cent for the adult. A smaller decrease between newborn and adult (21.8 per cent to 19.5 per cent) is shown by Falck's data for the dog.

Welcker and Brandt, in addition to data for various birds, reptiles, amphibia and fishes, give data from which the following have been calculated for mammals: bat, 19.5 per cent; shrew mouse, 3'oung, 21.1 per cent, adult (includes intestinal contents?), 31.7 per cent; mouse, 22.3 per cent; guinea pig, 17.6 per cent; hare, 16.3 per cent; sheep, 11.5 per cent; monkey, 12.8 per cent; ox, 10.3 per cent; elephant, 12.5 per cent. Sedlmair, for cat, finds 14.5 per cent; and Baumeister for adult pig, in medium condition, 6.0 per cent, fat, 9.8 per cent.

Voit, in the 6 dogs before mentioned, finds the visceral group forming 17 per cent to 22 per cent of the body. (Viscera in this case mclude blood, but not heart). When calculated on 'be fatfree, hair-free basis, however, unlike what was found for skin, skeleton and musculature, the variation scarcely appears less. In well-nourished animals, it was found to be 19 per cent to 22 per cent, and in the poorly-nourished, 17 per cent to 25 per cent.

In general, the smaller mammals have a relatively larger visceral apparatus, probably correlated with, a more intense metabolism. The rat occupies a somewhat intermediate position, the relative weight of the viscera being less than that of most of the small mammals, but greater than that of the larger mammals.

5. Remainder (tables 3, 4, 6; fig. 2). The remainder is the amount obtained by subtracting from the net body weight the weight of the skin, skeleton, musculature and visceral group. In addition to the liquids escaping from the tissues and body cavities and the loss by evaporation, it includes a few small unweighed organs (genitaha, aside from gonads, larynx, trachea, pharynx, oesophagus, large vessels) and varying amounts of fat in connection with the muscles and abdominal cavity.

It will be noted (table 4, fig. 2) that in the newborn the remainder forms a considerable proportion of the body (average 20.56 per cent) . It decreases, at first very rapidly, reaching an average of 13.68 per cent at 1 week, and then more slowly to 12.85 per cent at 3 weeks. From this time onward, it remains on the average rather constant, between 12 per cent and 13 per cent, but with considerable individual variation, due chiefly to the varying amounts of fat present. There is no evident variation according to sex; but in the gray rat the remainder appears low (table 6), probably because there is usually less fat present.

The remarkable decrease in the remainder during the first week naturally calls for an explanation. It cannot be due to varying amounts of fat, for no appreciable amount is visible at that age. There is likewise no considerable variation in the small organs included in the remainder. The decrease is apparently to be explained as follows. The newborn rat is very "juicy," or rich in water, with relatively large amounts of liquid in the interstitial tissue spaces as well as in the various cavities of the body. This excess of liquid largely disappears during the first week, and the remainder is thereby very markedly diminished.


In the human newborn, the remainder is apparently not more than 15 per cent. Vierordt's data give a remainder of about 18.1 per cent for the newborn, and 11.6 per cent for the adult. This, however, includes the intestinal contents. There is evidently a decline somewhere between the newborn and the adult, but data upon the intermediate stages are lacking. In the dog, as shown by Falck's data, the remainder is apparently about the same in the newborn (5.8 per cent) as in the adult (5.7 per cent). In a well-nourished cat, the remainder forms 3.5 per cent (Sedlmair). From data by Welcker and Brandt, remainders were calculated as follows: ox, 17.6 per cent; sheep, 14.5 per cent; mouse, 10.3 per cent; guinea pig, 7.9 per cent; hare, 7.2 per cent; monkey, 6.5 per cent; elephant, 4.8 per cent. The high proportion in the ox and sheep is due to their excess of body fat, and, as in the case of tlio nit, variations in the adults of other animals are apparently duv chiefly to difierenee in this respect.


In i-e«!;anl to the relative size of the various systems, as already mentioned for the component parts, practically the adult relations have been reached at the age of 10 weeks. This is evident from figure 2, but would appear still more striking if the horizontal distance beyond 10 weeks were increased to scale in proportion to the length of time up to 1 year. The only change of note after 10 weeks is the slight relative increase in the musculature, which is balanced by a decrease in the other systems, chiefly in the viscera.


Conclusions

The more important conclusions may be summarized briefly as follows:

  1. The head of the albino rat increases in relative weight from an average of about 23 per cent of the body in the newborn to nearly 26 per cent at 1 week. Thereafter it decreases in relative size, forming about 10 per cent of the body in the adult rat (age, 1 year).
  2. The upper extremities increase from about 7 per cent of the body in the newborn rat to about 9 per cent at 3 weeks, thereafter decreasing to less than 5 per cent at 1 year. The lower extremities increase steadily from about 9 per cent at birth to about 15 per cent at 1 year.
  3. The trunk decreases from an average of about 60 per cent of the body at birth to about 52 per cent at 3 weeks, increasing thereafter to about 70 per cent at 1 year.
  4. The skin increases rapidly from about 20 per cent of the body in the newborn to nearly 26 per cent at 1 week j^ thereafter it decreases steadily to about 18 per cen t at 1 year. ~^
  5. The skeleton increases slightly from an average of about 17 per cent of the body in the newborn to about 18 per cent at 1 week; thereafter it decreases steadily in relative weight, to about 10 per cent in the adult.
  6. The musculature decreases relatively from an average of 24.4 per cent of the body in the newborn to 22.8 per cent at 1 week; thereafter it increases steadily, averaging slightly more than 45 per cent of the body in the adult rat.
  7. The visceral group increases from an average of 18 per cent of the body in the newborn to about 21 per cent at 3 weeks; thereafter decreasing to nearly 13 per cent at 1 year.
  8. The remainder (net body weight minus skin, skeleton, musculature and viscera) undergoes a striking decrease from an average of about 21 per cent of the body at birth to about 14 per cent at 1 week. This is due to the disappearance of excessive liquids in the newborn. After 3 weeks, the remainder averages slightly more than 12 per cent of the body.
  9. The body of the- albino rat has practically reached the adult proportions in its component parts and systems at the age of 10 weeks.
  10. The data indicate no noteworthy differences between the sexes in the relative weight of the various parts and systems. With the possible exception of slightly heavier viscera and smaller remainder, the few data on the gray rat likewise reveal no marked difference in this form.


Bibliography

Baumeister, W. 1S90 Anleitung ziir Hchwcinezuclit und Schweinehaltung. 5 Aufl. Berlin.

Falck, C. Ph. 1S54 Beitriige zur Kenntniss der Wuchstumsges'chichte des Tierkorpcrs. Archiv. fiir path. Anat. (Virchovv's), Bd. 7.

Harless 1876 Lehrbuch der plastischen Anatomie. 2 Aufl. (cited by Vierordt)

Henneberg, W. 1878, 1880 Journal fiir Landwirtschaft. (Cited by Vinson, Beitriige zur Methodik der Analyse ganzer Tierkorper. Inaug. Dissert. Gottingen, 1904.) See also Referat von W. Henneberg, Ueber Fleischuud Fettproduction in verschiedenem Alter und bei verschiedener Ernahrung. (Nach Versuehen mit Schafen, auf der Versuchs-station Gottingen-Weende von Dr. E. Kern und Dr. H. Wattenberg ausgefiihrt.) Zeitschr. fiir Biologie, Bd. 17.

Jackson, C. M. 1909 On the prenatal growth of the human body and the relative growth of the various organs and parts. Am. Jour. Anat., vol. 9.

Lawes and Gilbert. 1859 Experimental inquiry into the composition of some of the animals fed and slaughtered as human food. Philos. Trans. Royal Soc, London, pt. 2.

Long, James 1906 The book of the pig. 2 Ed., London and New York.

Lowret, L. G. 1911 Prenatal growth of the pig. Am. Jour. Anat., vol. 12.

Martiny (date?) Arbeiten der deutschen Landwirts-Gesellschaft, H. 18. (Cited by Vinson, Beitrage zur Alethodik der Analyse ganzer Tierkorper. Inaug. Dissert. Gottingen, 1904.)

Meeh, Carl 1895 Volummessungen des menschlichen Korpers und seiner einzelnen Theile in den verschiedenen Altersstufen. Zeitschrift fiir Biologie, Bd. 31.

MtJHLMANN, M. 1900 Ueber die L'rsache des Alters. Wiesbaden.

Sedlmair, a. C. 1899 Ueber die Abnahme der Organe insbesondere der Knochen beim Hunger. Zeitschrift fiir Biologie, Bd. 37.

Vierordt, H. 1906 Anatomische, phj'siologische und physikalische Daten und Tabellen. 3 Aufl. Jena.

VoiT, Erwix 1905 Welchen Schwankungen unterliegt das Verhaltnis der Organgewichte zum Gesamtgewicht des Tieres? Zeitschrift fiir Biologie, Bd. 36.

Weiske, H. 1895 Weitere Beitrage zur Frage liber die Wirkung eines Futters mit sauren Eigenschaften auf den Organismus, insbesondere auf das Skelett. Zeitschrift fur physiologische Chemie, Bd. 20.

Welcker und Brandt. 1903 Gewichtswerte der Korperorgane bei dem Menschen und den Tieren. Archiv fiir Anthropologic, Bd. 28.



Cite this page: Hill, M.A. (2020, September 27) Embryology Paper - On the relative growth of the component parts and systems of the albino rat (1912). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_On_the_relative_growth_of_the_component_parts_and_systems_of_the_albino_rat_(1912)

What Links Here?
© Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G