Book - Russian Embryology (1750 - 1850) 7
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Blyakher L. History of embryology in Russia from the middle of the eighteenth to the middle of the nineteenth century (istoryia embriologii v Rossii s serediny XVIII do serediny XIX veka) (1955) Academy of Sciences USSR. Institute of the History of Science and Technology. Translation Smithsonian Institution (1982).
Publishing House of the Academy of Science USSR
Translated from Russian
Translated and Edited by:
Dr. Hosni Ibrahim Youssef # Faculty of Veterinary Medicine Cairo University
Dr. Boulos Abdel Malek
Head of Veterinary Research Division
Arab Republic of Egypt
The Smithsonian Institution and the National Science Foundation, Washington, D.C, by The Al Ahram Center for Scientific Translations 1982
The Smithsonian Institution and the National Science Foundation, Washington, D.C by The Al Ahram Center for Scientific Translations (1982)
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Chapter 7. The Work of Wolff: "On the Special Essential Tower"
In order to conclude a summary of Wolff's activities in embryology and to characterize them completely, it is necessary to stop at the idea which he frequently considered central to development and which was so differently evaluated subsequently. The idea is that of the essential power. In Wolff's works reviewed above, the essential power was mentioned either generally or sometimes in a very hazy form, or it was mentioned casually without sufficient explanation. Apparently, at the end Wolff found it necessary. to explain his point of view on this subject more definitely, and he felt the need to examine scientifically the power's control over the activities of organisms.
In 1782 the Petersburg Academy of Science, under Wolff's initiative (25), announced competition (26) for a prize on the question about the nature of the feeding powers. The subject of this work was formulated in the following manner. 1 In the introduction to the question, it was asserted that the nutritional juices were distributed among even those parts of the animal organism, such as the epidermis, nails, hairs, and horns, which, it was claimed at the time, were devoid of blood vessels. Further, it was noted that in the early stages of development of the embryo, in which there was not yet a heart, the blood vessels and the nutritional juices were also distributed homogeneously. From this it was concluded that the movement of the nutritional fluids, under the effects of such a power, is not dependent on the movement of the heart. Because juices similarly assimilate, grow, and form new parts throughout their life in plants, and because at the same time there is no other power comparable to the power of the heart movement, the movement of plant juices should also be described under the special power.
1 . The questions for the competition were given in Latin and submitted to the below-discussed manual "Zwo Abhandlugen etc." Here a shortened statement of the introductory part of the question is given. The text of the questions themselves is given in literal translation.
Therefore the following is asked:
What is the nature of that power, and in particular, is it identical with the commonly known powers, or is it, as they think distinguished from those and innate only to animals and growing plant substances? If the latter is true, the next question follows: of what general character is the effect of this power and by what properties is it distinguished from the general magnetic powers, indicating its exceptional nature?
In this competition, work from different countries was submitted. Among the twenty-four submitted works a large number were not worth serious consideration. Wolff reviewed all these works and, based on his opinion, two works were published: the article of J. F. Blumenbach (27), professor of medical sciences in Gbttingen, 2 and that of K. F. Born, doctor of medicine and surgery and ordinary lecturer at the medical-surgical institute in Kronshtadt. 3 Wolff combined his own article with these two articles, and they were printed together in one manual; Wolff's work presented his opinion about Blumenbach' s and Born's articles, but it mainly contained the statement of his own ideas. 4
The article by (Johann Friedrich) Blumenbach is entitled, "Attempt to answer the competition question, for the third time proposed by the Improvisator of the Academy of Science in Petersburg: Uti nutritio aequalibus etc.?" Born's article does not have a title, but was simply called "Second article on the feeding power."
The general topic of the manual appears on the title page as, "Zwo Abhandlungen uber Nutritionskraft, welche von der Kaiserlichen Academie der Wissenschaften in St. Petersberg den Preis getheilt erhalten haben. Die erste von Herrn Hofrath Blumenbach und zwote von Herrn Prof. Born. Nebst einer f erneren Erlauterung eben derselben Materie . " Von C. F. Wolff, der Akademie Mitglied, 1789.
Wolff's article is called "About the inherent essential power of the plant as well as of the animal substance. "5 its introduction compared Blumenbach' s and Born's opinions. It is written in quite a friendly tone and is concerned more with Blumenbach's theses, because Born's article was less original and to a certain extent full of citations from the previous work of Wolff and Blumenbach.
Wolff remarked that according to Blumenbach, the power or force which moves the nutritional juices is related, primarily, to the selective properties of the feeding tissues and, secondly, to the delivering force of the vessels or generally to the cavities containing those juices. On the contrary, Born found in the nutritional juices themselves the basis of the movement of the juices during feeding, growth, regeneration of the lost parts and healing of wounds. In other words the juices themselves acquire, in his opinion, the property of moving in definite directions. Without disproving any of the authors' opinions, he came to his understanding of the question.
First Wolff developed the idea ($1-5) that the nourishing power could not be related only to the hard or solid nourished parts of the body or only to the nourishing juice itself, but in his opinion, "it is inherent in the solid or hard, as well as in the fluid parts." ($ 4, p. 5) Turning to the character of the powers inherent in the living body ($ 6 - 8), Wolff stated his belief that these powers or forces are as such: reciprocal attraction of the homologous parts and repulsion of the heterologous parts in the nourishing juices, and also attraction between homologous solid and fluid parts and reciprocal repulsion of the heterologous parts ($ 7; p. 7). Consequent to that, there is an important observation that "defining and distinguishing the forces from each other cannot be done other than by their actions." ($ 8, P. 7)
Next comes a detailed justification of the existence of attractive C$ 9 - 16) and repulsive C$ 17 - 29) forces in the organisms. Then, after comparing his conclusions with Blumenbach's and Bom's ($ 30 - 36), Wolff discussed, in detail, the question about the means of movement of the nourishing juices, and he arrived at the conclusion that in the nourished parts there are no intervals and that the juices penetrate through a confluent substance ($ 37 - 66 and 69 - 71) . With that, he considered it as beyond doubt that the nourishing force could not be anything other than an attractive power ($ 67 - 68) .
5. "Von der eigenthumlichen und wesentlichen Kraft der vegetabi lis chen sowol als auch animalischen Substanz" (pp. 3 - 94) .
Wolff identified the attractive and repulsive power with the specific essential force of the plant and animal substance; hence, all the preceeding represents only an introduction to two basic parts of the work which consider the particularities of the essential force in the two living kingdoms. In the first part, which he entitled "About the distinguishing features of the specific essential force in the plant substance," Wolff confirmed that plants and their characteristic plant life do not develop as a result of attractive and repulsive forces which are common for all nature or of forces connected with the organization of the plant bodies. Hence the essential force, in his opinion, should be distinguished from those forces ($ 72 - 79) .
In the light of the conference works, published in 1784, this was a basic question: if the attractive force represents the cause of movement of the nutritional juices, then is it identical with the general attractive force which is inherent to all the bodies of nature, or if it is distinguished from it? Wolff remarked that this question was not even mentioned in any of the submitted works, although two of them contain a note that the authors considered the nourishing force as the usual force of attraction. "This question is of great importance and is easily solved," Wolff wrote. If the subject was as the authors thought, then plants, which are fitted with a general attractive force and acquire organization, could only be machines, distinguished from artificial machines only by their structures. In this case it would have been possible to construct from any material which is provided with a general attractive force, a model which not only in its external form but also in its internal structure could have been similar to one or another plant, such as the Tragopan pratensis L. This model must grow like a living Tragopanon, give similar flowers and seeds, i.e. reproduce, because it acquires the properties of this plant's organization and the same force. In other words it could have been the same machine. "I think, however," Wolff wrote,
that even the strongest defenders of mechanical medicine do not prescribe models of such function. Consequently, the nourishing force of the plants and animals should be distinguishable from the general force of attraction, which is characteristic of all the bodies of nature. This nourishing force should be inherent only in the plant and animal substance, because no other material except the plant and animal feeds, grows and multiplies. Because the entire life of the plantsâ€” -their nourishment, growth, vegetation and multiplication â€” depends on the nourishing force, it would be possible to call it inherent and an essential force ... Since animals eat, grow and vegetate (although the latter process extends not too long after development) and reproduce â€” and since their life depends on the nourishing force, this force must be considered an essential force which is characteristic of all vegetating bodies. ($ 72, pp. 38 - 39)
Further, Wolff stressed that for the vegetative life of plants and animals their structure is not essential. As proof he cited the boundless diversity of forms and the presence of living creatures (lichens, sponges, moulds) which do not have a defined external form and are devoid of structure (composed of either vesicles or of granular masses) . "All these living creatures simply could be accepted as living or vegetative material, and it is too difficult to consider them as organized bodies" ($ 73, p. 40). Another point in favor of the independence of the organism's vegetative function from its structure Wolff considered to be the decrease of the regenerative property with the increase of organization." "It is known," he wrote, "that the more perfect the regenerative property is in animals, the more imperfect is the organization of their body. How then could the vegetative functions be dependent on the organization?" (J 74, p. 40).
6. The belief that the degree of the regenerative property is in a strictly inverse relationship to the height of the
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Admitting that the forces characteristic of organized bodies promote the functions of vegetative life â€” in particular nourishment, vegetation, and multiplication â€” Wolff considered that these forces are sufficient bases for the functions mentioned. From this he concluded that "the mechanical causes interfere (where they exist) only accidentally in the activities of the proper vegetative forces and modify the activity, changing ... in particular the results of the form-making (vegetation) , which hence could reach an endless diversity" C5 75, p. 41).
Wolff's general conclusion he formulated in the following words, in which he simultaneously determined his relationship to animistic vitalism:
The essential force which is characteristic of plant and animal substance promotes vegetative functions without the participation of organization and without the effect of additional forces . This specific actual force is, apparently, particularly that force which was sought by (Bernhard Siegfried) Albinus, and its existence was admitted by Stahl and is ascribed without basis as its spirit. It represents a special defined relation to the attractive and repulsive forces. t$ 77, p. 42)
Later, however, Wolff wrote the following:
So far as the vegetative life of plants and animals depends only on a force, because the organization does not add anything, it is fair to consider this organism was dominant in the literature until recently. Only recently, M. A. Vorontsov has given essential indicators of the incorrectness of this prevalent belief (M. A. Vorontsov, "Regeneration of organs in animals" (Regeneratsiya organov v zhivotnykh) , 1949, SOV. NAUKA, pp. 82 - 88).
force as distinguished from the general attractive and repulsive / forces of all the other bodies. It should be characteristic only for developing bodies, including, as we know, only plants and animals. This force acquires the property of attraction as well as repulsion. It must, therefore, get a particular definition, i.e. must represent special kinds of attractive and repulsive forces. ($ 79, p. 42)
Then Wolff considered in detail the character of the actual force. He considered it to be established that the plant substance attracts the homologous substance and replaces the heterologous substance ($ 81 - 82) , on which property is based, in both plants and animals, the capability of producing the plant and animal substances ($ 83 - 84) . According to Wolff, the main vegetative functions of the animal organism are connected with the essential force: the digestion and formation of the milky juice (5 85), blood formation ($ 86 - 87), and finally the secretions. This latter function he particularly reviewed in detail C$ 89 105) . Wolff subsequently mentioned another feature of the essential force on which the plant substance depends, not only to attract to itself the homologous substances, but also to mix with them ($ 110) . This feature Wolff considered important and indicative that the attractive force of the plants and animals becomes a nourishing force C$ HI - 115) . Comparing the appearance of the essential force in plants and animals led Wolff to a conclusion that "Therefore, in plants and animals there is only one essential force" (p. 65).
Reaching the conclusion that the essential force is single, Wolff again turned to the question about the nature of this force. "It was possible," he wrote,
to call it the spirit of the plant and the vegetative part of animals, but not, of course, in the philosophical meaning of this word, but only in a general sense of force which determines all features which taken together constitute the life of things. If I am not mistaken this is the same spirit which was acutely observed by Stahl and the defenders of his opinion in the vegetative functions, but which they mixed, without basis, with the spirit of animals ....
Because in nature all can be related to attraction and repulsion, and both of these primary actions originate from the same force, it seems to me, if I may express my opinion, that in all nature only one single force exists, namely the force of attraction and repulsion . . . and there are not many forces, but only one force. ($ 124, pp. 69 - 70)
Coming to the animal functions, the study of which constitutes the second part of the work, Wolff remarked that his opinions have a less conclusive character. First of all he drew attention to animal functions which are effected by stimulation of the nerve substance and muscular action and which, at first glance, are promoted by special forces: the first is sensitivity, and the second is irritability. "Both of these forces should be completely distinctive and distinguishable from the essential forces of plant substance; they must constitute the essential force of the animal substance, i.e. on which all the animal functions depend" ($ 137, p. 77). From the analysis of these features, Wolff formulated a cautious conclusion that a relationship exists between irritability and the repulsive force 138) , and he discussed the initiating cause of irritability as identical to the essential repulsive force C$ 141, p. 79). CSigismund) Kohlreuter carried out investigations based on this opinion, which he described in an article sent to the Petersburg Academy of Science. (28)
Wolff concluded from these data that "It is more than evident that irritability is inherent in the plant substance in general, as in the animal, and that irritability by any means does not represent the essential force of only the animal substance" C$ 150, p. 85). From this he drew the conclusion of the single nature of the essential force in plants and animals; it is distinguished only by a different animation effect (5 152, p.. 86). The analogy allowed Wolff to think that irritability is based on the force of repulsion, as sensitivity is on attractive force.
The concluding paragraph begins with the statement: "Considering that the essential force of the plant and animal substance is inherent to these substances, no one will doubt that the initial existence of the force itself has been shown." On the question, "does the essential force depend on the entire aggregation of the substance with which it is characterized, i.e. on all the substance, or does it depend mainly on one constitutive part, or on individual substance which can be considered as the constituent part of the living animal and plant substance, but separated from it?" Wolff answered that "for me the latter, for many reasons appears much more evident." (Â§ 178, p. 94) Remarking that in regard to the essential force of the animal substance there were yet many things which were not clear, Wolff ended his work with the following words: "Concerning the essential force of the plant substance, I do not believe that I have made a mistake on any important point."
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