Book - Russian Embryology (1750 - 1850) 11
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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 11. Louis Tredern - The Forgotten Embryologist of the Beginning of the Nineteenth Century
Before going into the characteristics of this turning point in the history of embryology, which is known by Baer's classical investigations and Pander's earlier work, it is appropriate to review the dissertation of L. Tredern, published in 1808.
The personality of this embryologist, who so brilliantly began his investigative work and then unexpectedly disappeared from the scientific horizon, had long remained veiled. K. M. Baer, who was always actively interested in the history of science in Russia, and particularly in his homeland in the Prebaltic, took pains to clarify the conditions of Tredern' s life and work; Baer published the results of his search in a special article. ^ In 1901 the late professor of Dorpat University, Ludwig Steida, who is known for his review of Russian work in histology and embryology, printed the Latin text of Tredern' s dissertation translated from the German. He prefaced this with an introductory article containing a biography of Tredern, which drew additional information, particularly from Baer's papers. 2 in 1927, M. M. Solovev gave some new data about Tredern, contained in a letter from K. M. Baer to the famous Russian teacher I. F. Krusenshtern. 3
K. E. v. Baer, "Biographische Nachrichten uber den Embryologen Graf en Ludwig Sebastian Tredern," BULL. ACAD. SCI. ST. PETERSB., 19 (1874), pp. 67 - 76. L. Stieda, "Der Embryologen Graf von Tredern und seine Abhandlung uber das Huhnerei," ANAT . HEFTE. BEIT. U. REFERATE Z. ANAT. U. ENTW. , Part I, Bk. LVTII, Vol. XVIII (1901), pp. 1 - 69.
In his article about Tredern, Baer mentioned how in 1817 he was engaged in comparative anatomy with DOllinger and assisted in the organization of Pander's embryological studies. On becoming acquainted with the dissertation of the Count Tredern, he was surprised by its thoroughness and accuracy in observations and drawings. Being interested in the personality of this investigator, Baer asked Do'llinger about him and received the answer, "You know him; you know that he is also from Estonia." Slightly surprised that he did not know a fellow countryman, Baer decided that on returning home he would get information. However, in Estonia there was no trace of the Count Tredern. Doctor Vettershtrand, working on the "Biographical Dictionary of the Activities of Liflyandi, Estlyandi and Kurlyandi," could not tell anything about Tredern, and explained only that some years before, when the Russian fleet was stationed in Revel, a naval officer lived there who had on his ship a brood hen and diligently watched the growth of chickens. The people of Revel remembered this strange naval officer, but nobody could remember his name. This gave Baer his first clue. After that, the search for Tredern yielded no results. In Petersburg, Baer wrote on April 7 and June 24, 1836, two articles for the Prebaltic newspaper DAS INLAND, 4 i n which a short account of Tredern f s dissertation was given and its significance noted. He expressed surprise that Count Tredern' s family had disappeared in little Estonia without any trace, and that nobody could remember anything about them. In the first of these articles, Baer appealed to his fellow countrymen, especially to those who during 1806 to 1808 had studied in Jena and Gottingen, to ask whether they knew anything about Count Tredern. The information he received led, according to Baer, only along a false trial. In 1874, when Baer wrote his article on Tredern, he obviously forgot completely that in 1836, undoubtedly in answer to his call, he had received a letter from the notary Shtender from Libava with very useful information about Tredern. Enclosed in the letter was even an autograph of the mysterious embryologist. The contents of this letter are mentioned below,
M. M. Solovev,"Correspondence of the Academician K. M. Baer with Admiral I. F. Krusenshtern. First Collection of the Memoirs of Baer." Publications of the Academy of Science USSR, 1927. pp. 10 - 59.
K. E. v. Baer, "Bitte um eine Nachricht iiber die Litteraturgeschichte unseres Vaterlandes, besonders an die jenigen Herren gerichtet, welche in den Jahren 1806 - 1808 in Jena oder Gttttingen studiert haben," DAS INLAND. EINE WOCHENSCHRIFT Ft)R LIV-, ESTH- UND KURLANDISCHE GESCHICHTE, GEOGRAPHIE, STATISTIK UND LITTERATUR (1836), No. 15, pp. 253 - 256. "Wegen des Graf en von Tredern zweite Auf forderung, " ibid. (1836), No. 23, pp. 391 - 392.
Baer also called upon Admiral I. F. Krusenshtern for help, and in a letter of May 26, 1836, he requested his assistance. In this Baer mentioned, incorrectly, the later assumption that the senior Tredern had stayed in Revel with his ship. There his son was born, who considered Estonia his country. Because the young Tredern was later a Russian naval officer, it was natural to assume that he studied in the Petersburg Navy Corps.
"Would Your Excellency," wrote Baer to Krusenshtern, "with the advantage of your post, please search in the registers and archives of the Russian fleet 1) for an officer with the family name of Tredern who may have spent some time in Revel. 2) Did he father a son there and what was his name?" In an article on Tredern in 1874, Baer indicated: "in the files of the navy, which were reviewed according to my request, this given name was not known."
Continuing with the story of his search, Baer described how in 1839 or 1840 he got his first clue, when in the populous community of Petersburg he again asked if anybody knew Count Tredern, accidentally pronouncing this family name with the accent on the last syllable. One of the ladies present, daughter of the statistician, the academician Shtorkh, said that they knew Count Tredern in the house of the banker Ralle, whose widow lived at Vasilev Island, and even mentioned in what house. The widow Ralle was found, and she remembered well the father of the missing embryologist. He was a French emigre who was in Russia in Tsar Paul I's time, from whom, apparently, he had received the title of count. Later Baer corresponded with Gebenbaur and Katfazh and received from them some documentary data on Tredern.
On the basis of the available materials, biographical data about Tredern can be briefly stated as follows. The family of Tredernov, whose name indicates their Celtic origin, previously lived in Brest. The younger line of this family, to which the embryologist belonged, was named Tredern de Lezerec. The embryologist ! s father, Jean Louis Tredern de Lezerec, was a captain in the French fleet and a mathematician. On September 14, 1780, when Captain J. Tredern was inspector of the naval college in Brest, he became father of a son who received the name Louis Sebastien Marie. The elder Tredern participated in the War of the Vendee on the side of the mutineers and royalists, and after the defeat at the Quiberon peninsula in the summer of 1795 he emigrated to Russia with his son Louis Sebastien, who at this time was not yet fifteen years old. Nothing reliable is known about the years of education of the future embryologist in Petersburg. There is reason to assume that he studied in the Petersburg boarding school Abbot Nicollia, where his father apparently was teaching mathematics, and then went into the Navy. In any case, it is known that on October 4, 1797, Louis Sebastien Tredern enlisted as a naval cadet in the Russian fleet on the ship "Pimen," which was stationed for a long time in Revel. The young Tredern lived in Revel for four years, information on his presence there existed from individuals who knew him personally and who confirmed the fact that this young man, besides serving in the fleet, had studied and was occupied with investigations in natural history. Thus a certain person named Gamper, from whose father Tredern h ad hired a flat, stated that this remarkable sailor had turned his room into a true open-air cage for birds, which lived there on specially placed saplings. Another person living in Revel, a retired Russian general of Livron, said that he was a neighbor of Tredern f s and frequently helped him to watch dogs, cats, rats, and other animals.
In the summer of 1801, warrant officer Louis Tredern resigned in order to accompany his ailing father abroad, and both of them left Russia in August. The father returned to France, where he died after some years, and the son involved himself with medicine and the natural sciences in Germany. It is not known in which university he studied. It is known only that in October 1804 Candidate of Science Count Sebastian Tredern was enrolled in Wiirzburg University. In this period he worked with D61 linger, which D61 linger later reported to Baer. Having missed the opportunity of conducting an inquiry about Tredern in Wiirzburg, Baer was uncertain about him, because fifty years later, at the moment when Baer was working on his article on Tredern, there was no one still living who could remember him there.
In the introduction to his dissertation, Tredern stated that in the summer of 1807 he was busy studying comparative anatomy (obviously, in Wiirzburg in DCllinger's laboratory), and in the autumn he travelled to Gtfttingen, where he consulted with Blumenbach about his embryological and comparative anatomical investigations.
Tredern wrote further that he had, at the beginning, the intention to publish an extensive work on avian embryonic development, but he had heeded Blumenbach' s advice and instead began writing a dissertation to obtain a doctoral degree, including in it only a small part of his data and prepared drawings. With Blumenbach' s recommendations and assistance, Tredern, in the winter of 1807 - 1808, studied embryology in Gottingen's rich library and at the same time continued his study of incubated eggs, overcoming the great difficulties of such wintertime study. In his dissertation, Tredern mentions with gratitude the official prefect Tsakhar and his wife, who assisted him in getting the material for his investigations. Tsakhar 's son had told Baer in 1865 that Tredern, whom they thought Swedish, had passionately pursued the study of chick embryos, and frequently came to them at home with opened eggs and showed them the course of development of the chick. The famous zoologist K. Siebold wrote to Baer that in the winter of 1825 - 26, he heard in GOttingen Blumenbach 1 s lecture favorably defending Tredern' s work and, with his characteristic humor, added that the GCttingen housewives were claiming that Tredern was causing the price of eggs to rise.
In April 1808, Tredern left for Jena, apparently with a prepared dissertation. It is not known if he associated with Oken there. At any rate, Oken, talking about Pander's dissertation, wrote that "Tredern 's dissertation . . . was accomplished in our laboratory," so "in our laboratory" could mean only in Jena. 5 But it is not evident, first, that Tredern's dissertation was accomplished in Jena, and, second, that Oken had any connection to it. In 1808 Oken was not in a position to evaluate the significance of Tredern's dissertation, so that even after ten years he could write about Pander's dissertation in statements indicating a complete misunderstanding of the subject. (52)
In the spring of 1808, Tredern passed the examination rigorosum honorably, and, after defending his dissertation on April 4, he received the degree of Doctor of Medicine and Surgery. Tredern thereupon returned to GSttingen, where he continued working intensively on the study of avian development. It was about that second period of Tredern's life in Gottingen that the notary Shtender had the memories mentioned above. This letter, lost by Baer and recovered by Stieda, is interesting enough for us to extract detailed quotations.
Tredern, my friend from student years, will always live in my memories. I cannot give a convincing answer to the question as to where he disappeared. In autumn, 1808, nearly within half a year after my arrival in Gottingen, Tredern also was present.
He was a man of strong physique, 5 feet 3 inches tall, with dark hair, large whiskers, brown eyes, and a fairly large, slightly arched nose. He was, according to our judgment, about twenty-four years old. 6 He had a quiet and at the same time an active character. He lived very economically, did not indulge in any vices, and constantly wore a suit of dark brown cloth, gray trousers, and a black cloth hat with a sharp, downwardhanging brim. He carried a brush like those carried by our military people thirty years ago. He was present only with small groups of people, especially with Blumenbach. He spent all of his time on the incubation of the eggs of different birds, mainly chickens, and in drawing the embryos from the beginning of incubation to the time the chick hatched from the shell. However, he displayed an almost incredible endurance, was literally skin and bones because he forgot about eating, drinking, and sleeping, and was sustained only at the pipe which he rarely took from his mouth. For his observations he had some tin and clay containers fitted with a thermometer and usually heated by oil or alcohol lamps, or, rarely, with charcoal; the eggs were placed there in clean white sand. Because my presence did not interrupt him, I frequently visited him. We smoked and talked, and during this time he moved from one container to another carrying out drawings of the opened eggs. He was capable of doing that with thoroughness. Since the drawings and the features represented were similar from one egg to another, the speed and easiness with which he drew frequently left me in amazement.
5. Oken, ISIS, No. 192 - 193 (1817), p. 1531.
6. In 1808 Tredern was actually twenty-eight years old
Shtender enclosed with his letter a paper from an album which Tredern had given him as a farewell gift, showing a view of Jena and the embryologist's autograph (Figure 17). On the above right was written: "Kennst du das Land, wo die Kartoffeln blfihen? Lebe wohl und denke an mich. Dein Freund und Binder S. G. Tredern. "7 On the left is the inscription "Memoria der Fuchse."** Below the picture is the date: 17/3 1809 Gottingen. "A country where potatoes grow," in Tredern' s words, "by which you must mean GCttingen, where potatoes are extensively cultivated and where poor students feed mainly on them," giving it a humorous nickname pointing out their gastronomical predilection.
Where was Tredern in the period from 1809, when he left Gottingen, to 1811, when he appeared in France? Again it is not known. In the summer of 1811 in Paris, Tredern passed the government examinations, obtaining the right to practice medicine in France. He based his thesis on the subject of the organization of hospitals. After that, he joined the French fleet as a physician. He travelled to Guadaloupe, where he died unmarried. The date of his death is unknown.
7. "Do you know the place where the potatoes grow? Live well and remember me. Your friend and brother S(ebastian) G(raf) Tredern . "
8. "Memory of fuchse." "Fuchse" are incoming students, frequently subjected to the mocking of the members of the student corporations.
Figure 17. Autograph of Louis Sebastian Tredern, on a print showing a view of Jena.
This quick and incomplete biographical account indicates a rich life. It draws a portrait of a man who was capable of untiring and selfless activity in his scientific interests, together with a tendency towards wandering. He was transferred as a child from Brittany to distant Petersburg. From there in his youth, with an already developed scientific interest, he travelled to Revel. As an adult he went to Germany where he moved from one university city to another: Wiirzburg, Gottingen, Jena, and again Gtfttingen. Later he was in Paris and, at the end, in Guadaloupe, on the shores of America. This biography could be material for an interesting story, but it does not give more than a picture of the life of a wonderful, independent investigator. Yet in 1836 Baer noted, in comparing Tredern's life story with the fate of the mysterious foundling Kaspar Hauser, that his dissertation was as amazing as the author himself. "I would have doubted," wrote Baer, "the existence of this dissertation if it were not directly in front of me."
Tredern's dissertation finds a place in the history of embryology in Russia, despite the fact that the author was not a Russian, was not born in Russia, and lived there only six years. There are two reasons for this. First, while living in Petersburg, Tredern developed a deep interest in the problems of comparative anatomy, and especially embryology, which he worked on first at Revel, and then in Germany. It is hard to believe that there was a source for this interest other than the work of K. F. Wolff, who had died one year prior to Tredern's arrival in Russia. Especially in Petersburg, Tredern could have been acquainted with Wolff's classical work, which had elucidated the embryonic development of the chick intestines, and he might have found in this work the impulse for similar study.
The second reason for listing Tredern among Russian embryologists is the fact that he considered himself as such. The title page of his dissertation clearly identifies the author as "L. S. Tredern, Estonia â€” Rossus." After losing his motherland, Tredern obviously considered Russia his country, the place where he successfully started his investigations. It is highly probable that his designation of national affiliation in the dissertation implied an intention to return to Russia. It has been explained why this intention was not accomplished.
The aim of Tredern' s dissertation was to tell the preliminary story of the avian egg and its hatching. He submitted his dissertation for open public discussion by scientists on April 4, 1803. 9 The introduction contained an important statement specifying the extensive material to which the author had referred, presented in several divisions. These divisions are:
I. NATURAL HISTORY OF THE EGG. Color, form, size, weight, and taste of the egg, properties of the shell, the behavior of birds during incubation and its duration, the number of eggs, and so on.
II. ABNORMALITIES OF EGGS (deviations from normal structure) . Information was included about eggs becoming luminous in the dark, about eggs turning into glass and amber, and even about cocks laying eggs. The last case, obviously, deal with hens displaying feathers like those of cocks, or having voices like those of cocks, features which are not rare, but which promote superstition.
III. CHEMISTRY OF EGGS. This division included investigations about the effect of different reagents and physical agents (temperature and humidity) on individual constituents of the egg.
IV. INCUBATION OF THE EGG. Tredern wrote that he had carefully investigated eggs from the first hours of incubation, from the appearance of a recognizable embryo to the hatching of the chick, partly with the naked eye, partly with the aid of a lens, accompanied by descriptive, life-size drawings. In this section he reported changes in the egg membranes, including the amnion and chorion, during the whole period of incubation, the changes in the yolk and the egg white, and also in the amniotic fluid and the blood- carrying vessels (obviously those outside the embryo) . There is also an explanation of fetal development; hence the changes of the individual organ systems were followed. The dissertation mentioned that many systems of the growing embryo had not been investigated by previous authors, especially the muscular, circulatory, and nervous systems. On the development of the skeleton, there was an earlier book by Haller. With regard to the internal organs, Tredern noted that many authors had thoroughly studied heart development; other organs were investigated with more or less detail, but he found no data about some, such as the fibrous sac, uropygial glands, and the pancreas. Tredern sought to correct mistakes and to fill gaps in his predecessors' investigations. He modestly observed that his beginning should receive support through verification by other scientists.
Tredern, DISSERTATIO INAUGURALIS MEDICA SISTENS OVI AVIUM HISTORIAE ET INCUBATIONIS PRODROMUM, QUAM PRO GRADU DOCTORIS SUMMISQUE IN MEDICINA ET CHIRURGIA HONORIBUS, PRIVILEGIIS AC IMMUNITATIBUS RITE CAPESSENDIS, A.D. IV Aprilis MDCCCVIII publico eruditorum examini subjecit Ludovicus Sebast. Comes ab Tredern, Estonia â€” Rossus, Jena.
V. THE CHICKEN AFTER HATCHING FROM THE EGG. Here he mentioned only a few areas subjected to study, such as the disappearance of the yolk and the yolk duct.
VI. This division was entitled "Notes about Books," and was composed of explanatory notes on the list of works on embryology and related questions in the Gottingen library.
The above list of problems represented such an extensive plan of work that, according to Baer, no individual could have accomplished it without achieving immortality. "This report," Baer continued,
occupies four pages (of sixteen) , and inevitably the suspicion creeps in that the author gave only the list of what he planned to investigate. But later he provided accurate descriptions and defined observations with abundant references to his predecessors, indicating that the author knew the literature of his subject completely. The references include K. F. Wolff's work on the intestines, which almost nobody had known until Meckel made his well-known German translation in 1812. The same observations in Tredern 's dissertation are stated very briefly and accurately, which requires us to acknowledge the author's unquestionable talent in minute anatomical investigations. An outstanding feature is a table engraved on brass (Figure 18) . It is very simple, almost just outlines, but in accuracy and richness of detail it surpasses the brevity of the text. I could have characterized the table best by saying that with the exception of the earliest period of life of the embryo, which was not presented there, the table was richer in its content than all that was published earlier concerning this question. The later series of engravings by the Englishman Ham do not give one-fourth the clarity presented by this outlined drawing. It is as if the author wanted to be provocative, using line drawings and leaving to posterity the question of who he was and where he had gone. It is necessary to remember that he wrote in 1808, for four years after which not a single significant work on the development of the chicken appeared. He was considered the principal founder of a new series of investigations. Being the first in this respect, he had no guide, because there were none who could have assumed this leadership. 10
It will be useful to give a brief statement of those sections of the dissertation in which are described those more or less complete observations and the wonderfully specific drawings. These observations concern the paunch (cicatrice), the albumin ligaments, the development of the jaws and beak with its hillock, the yolk-intestinal duct, the digestive tract, and the extremities. Below are given Tredern' s data, references, and comments in the form of notes at the end of the book.
THE PAUNCH, OR CICATRICE, was called by the old embryologists the cock's trace or cover. It later received the name embryonic layer or embryonic disk. Tredern only mentioned that he could observe this formation on the surface of the egg yolk while they were still in the ovary, something that none of his predecessors had succeeded in doing CFigure 18, 1).
10. The stated opinion of Baer was taken from two of his articles about Tredern, in DAS INLAND (April 7, 1836) and in BULL. ACAD. SCI. ST. PETERSBURG, 19 (1874) .
Figure 18. Table of illustrations from Tredern's DISSERTATIO . . . OVI AVIUM HISTORIAE ET INCUBATIONIS PRODROMUM.
Fig. 1. Internal parts of domestic hen: 1- aorta;
2- mesenteric vessels; 3- large intestine; 4- rectum;
5- cloaca; 6- caecum; 7- fat; 8- yolk of the egg in the ovary; 9- groove; 10- vessels of the yolk membrane;
11- attachments of round ligament; 12- infundibulum;
13- curvature of the uterus; 14- cervix of uterus;
15- peritoneal ligament of the uterus; 16- stretched uterine
ligament; 17- anal opening; 18 and 19- its external and
internal pulp; 20- feathers; 21- faeces; 22- villous membrane
of the intestines; 23- bowl;
Fig. 2. egg, opened under water: 1- shell; 2- second white;
3- third white; 4- chalaza; 5- yolk; 6- belt of yolk membrane; 7- corrugations of yolk membranes; 8- cervic of white ligament; 9- stretched white ligament; 10- transparent part of the ligament; 11- second proper ligament of the egg; 12- first proper ligament of the egg; 13- groove;
Fig. 3. view of the embryo from the front. Third hour of the 4th day of incubation: 1- brain; 2- eye; 3- forehead;
4- rudiment of the upper jaw; 5- opening of the beak;
6- upper jaw; 7- heart; 8- vertebrates; 9- wing; 10- legs; 11- tail; 12- chorion; 13- yolk duct; 14- vascular zone;
Fig. 4. 6th day of incubation: 1- forehead; 2- eye; 3- opening of the beak; 4- dorsum of the beak; 5- its lateral parts; 6- basis of the upper parts of the beak; 7- fissures of the future nostrils; 8- upper jaw; 9- trachea;
Fig. 5. 8th day of incubation: 1- beak dorsum; 2- nostrils;
3- basis of upper jaw; 4- lower jaw; 5- beak opening;
Fig. 6. twelfth hour of the 9th day: 1- nostrils; 2- node
on beak dorsum; 3- lateral parts of the upper jaw; 4- opening
of the beak; 5- lower jaw;
Fig. 7. 1- forehead; 2- nostrils; 3- node of the beak;
4- lateral parts of the beak; 5- lower jaw; 6- trachea, visible through tectum;
Fig. 8. 13th day: 1- nostrils; 2- beak node; 3- parts of the upper jaw; 4- lower jaw; 5- trachea;
Fig. 9. 16th day; cartilaginous capsule of the beak from the side: 1- beak node; 2- nostrils; 3- upper capsule;
Fig. 10. 19th day: 1 and 3- as in Fig. 9; 2- lower part of the lower jaw;
Fig. 11. domestic goose, 8th day of incubation: 1- amnion with corrugations, caused by the effect of water; 2- chorion; 3- place of union of proper membrane of yolk with chorion and amnion; 4- cut membrane of yolk; 5- opening of amnion, or navel; 6- small intestine; 7- yolk duct; 8- vascular zone; 9- its lateral parts; 10- left leg; 11- rudiments of fingers; 12- uropiges; 13- tail; 14- heart; 15- forehead; 16- brain with vessels; 17- eye;
Figs. 12-15. 8th, 10th, 11th and 12th day: 1- fingers;
Fig. 16. 1- swimming membrane; 2- claws;
Fig. 17. 17th day: 1- claws; 2- elongated scales; 3- wartshaped scales;
Fig, 18. 21st day: 1- claws; 2- elongated scales; 3- remnants of swimming membrane; 4- wart-shaped scales;
Fig. 19. sixth hour of the 4th day: 1- chorion; 2- amnion;
3- vascular zone; 4- yolk membrane; 5- intestines; 6- navel; 7- tail; 8- leg; 9- wing; 10- aorta; 11- heart; 12- lower jaw; 13- forehead; 14- brain; 15- eye;
Fig. 20. 6th day: 1- oesophagus; 2- craw; 3- stomach;
4- duodenum; 5- pancreas; 6- small intestines; 7- yolkintestinal duct; 8- rudiment of caecum; 2- rectum; 10- cloaca; 11- vascular zone;
Fig. 21. 9th day: 1- oesophagus; 2- craw; 3- tendinous part of the stomach; 4- muscular part of the stomach; 5- duodenum; 6- pancreas; 7- small intestines; 8- yolk duct; 9- vascular zone; 10- yellow vessels; 11- rectum; 12- cloaca; 13- anal opening; 14- large intestines; 15- caecum;
Fig. 22. 1- oesophagus; 2- craw; 3- tendinous part of the
stomach; 4- muscular part of the stomach; 5- duodenum;
6- pancreas; 7- small intestine; 8- caecum; 9- rectum;
10- cloaca; 11- anal opening; 12- large intestine; 13- vessels
of the yolk; 14- yolk duct; 15- its inf undibulum ; 16- yellow
Fig. 23. 12th day: 1- heart with pericardium; 2- liver; 3- tendinous part of the stomach; 4- muscular part of the stomach; 5- duodenum; 6- pancreas; 7- caecum; 8- large intestine; 9- small intestine; 10- rectum; 11- cloaca;
12- anal opening; 13- yolk duct; 14- yolk vessels; 15- yellow vessels;
Fig. 24. 16th day: 1- heart with pericardium; 2- liver;
3- craw; 4- tendinous part of the stomach; 5- muscular part
of the stomach; 6- duodenum; 7- pancreas; 8- small intestine;
9- large intestine; 10- caecum; 11- rectum; 12- cloaca;
13- anal opening; 14- yolk duct; 15- yolk vessels; 16- yellow vessels; 17- chorion vessels;
Fig. 25. the twelfth hour of the 18th day: 1- intestines;
2- yolk vessels; 3- yolk duct; 4- yellow vessels;
Fig. 26. 18th day: 1- heart; 2- liver; 3- tendinous part of the stomach; 4- muscular part of the stomach; 5- chorion vessels; 6- duodenum; 7- pancreas; 8- small intestine; 9- yolk vessels; 10- yolk-intestinal duct; 11- yolk duct; 12- yolk membrane; 13- cut amnion; 14- cut navel;
Fig. 27. 28 hours after hatching: 1- intestines; 2- yolkintestinal membranes; 3- yolk vessels; 4- yellow vessels;
Fig. 28. 1- intestines; 2- yolk-intestinal duct; 3- yolk vessels; 4- yellow vessels;
Fig. 29. 4th day after hatching; the same legends;
Fig. 30. 4th day after hatching: 1- craw; 2- oesophagus;
3- trachea; 4- neck; 5- lever; 6- stomach; 7- muscular part of the stomach; 8- tendinous part of the stomach; 9- duodenum;
10- pancreas; 11- small intestine; 12- remnants of the navel;
13- yolk; 14- anal opening? 15- thigh (femur); 16- wing; 17- sternum; 18- remnants of cut abdominal muscles; 19- feathers;
Fig. 31. 16th day after hatching: 1- intestines; 2- yolkintestinal duct; 3- remnants of the yolk;
Fig. 32. 20th day of incubation: 1- navel; 2- corrugations of covers around navel; 3- umbilical vessels; 4- shell; 5- chorion; 6- right femur; 7- right leg; 8- beak; 9- basis of wing; 10- wing; 11- neck; 12- head.
THE ALBUMIN LIGAMENT (Ligamentum albuminis) is the structure located, so Tredern thought, on the border between the external fluid and the internal thick egg albumin. These two layers of egg albumin Tredern called the primary and secondary egg albumin respectively CAlbumen primum and Albumen secundum) . In detail he described the different parts of this ligament and its relation to water and acid; in short, he did not doubt its constant existence. Later, however, Baer showed that the structure did not represent an independent membrane or ligament, but only the surface layer of the second (middle) layer of the albumin which was connected with the first (external) layer at the pointed end of the egg. This membrane, according to Baer,! 1 appeared only in an egg opened in water. Upon removal of the membrane formed in water, it developed again. Baer agreed with Purkinje, who considered the reproduction of the membrane as evidence that it was not a constant structure but only a result of water acting upon the surface of the thick albumin.
DEVELOPMENT OF THE JAWS AND BEAK. Some earlier authors had noted the presence of the beak at about the fifth day of incubation (Haller, Wolff, Malpighi) (53) and some had related its appearance to different periods of embryonic life (Koiter, Vesling, Stenon, Lengli, and Shrader) (54) . Tredern concluded that on the fifth day (rarely, on the fourth day) it was possible to see the first beginnings of the beak. Occasionally the lower jaws appeared earlier than the fourth day, when along the sides of the neck two branches appeared. The upper jaw is usually seen somewhat earlier than the lower, but its halves remain disconnected longer. The central growths of the upper jaws from the forehead have at first the shape of a cluster (Figure 18, 36, 46). They are separated from smaller blunt growths by two slits (Figure 18, 4), which later are converted into the nostrils. These blunt growths later Cat the fifth day) join with the side parts of the upper jaw CFigure 18, 36, 45). The forehead cluster gradually forms the back of the upper jaw (55) (Figure 18, 44, 51). On the seventh or eighth day the beak starts to be covered with a cartilaginous case, which is almost always more constructed in the upper jaw than in the lower (56) . This cartilaginous capsule gets its beginning from one small white spot, which later is converted into the top of the beak. Simultaneously with the conversion of the beak into a cartilaginous mass, an elevated white spot appears on it (57) , having a top which on the tenth day is the size of a small pinhead. On the eighteenth day the top of this elevation has the shape of a spike, which the chick uses at the time of hatching to break the membranes and perforate the shell. Within one to two days after hatching, the prominence on the beak falls off; however, its remnants can be seen for some time.
11. Baer, UBER ENTWICKLUNGSGESCHICHTE , Vol. 2 (1953), p. 22.
INTESTINAL YOLK DUCT. This formation Tredern called the stem or the apophysis. According to his data, the intestinal yolk duct is formed on the fourth day of incubation, after the closing of the intestinal canal, as a delicate extension as of a narrow gut through the opening to the abdominal cavity (58) (Figure 18, 19(5)). Later, the length of the duct increases, and apparently it is composed of a membrane and a gut. The connection between the yolk and the intestine through this duct shows that it is possible to blow into the intestine from within the yolk sac. Because this is not always possible, some authors doubted the existence of an opening in the yolk intestinal duct (59). However, other investigators, for example Vicq d'Azyr and Blumenbach, regarded this experiment as successful. The remains of the yolk intestinal duct are seen after hatching in the form of a narrow mesentery (Figure 18, 27(2)). The remains of the mesentery can be observed up to the seventeenth day after hatching, and in some birds, especially swimming birds, throughout its life (Figure 18, 31(2)).
INTESTINAL CANAL. Tredern considered the digestive canal only from the stomach to the anus, and he described its changes during incubation. On the fourth day it is possible to see the intestinal canal with a lens (60) . In this period it has an equal diameter throughout its extension. Tredern noted the great accuracy of Wolff's work in the NEW COMMENTARY OF THE PETERSBURG ACADEMY OF SCIENCE, especially in his third section. Because Wolff had studied intestinal development under a microscope, and not with a lens as Tredern did, the latter did not consider that he could add anything to Wolff's description.
Referring to Wolff's work, Tredern said that the intestine is formed of the mesentery (61) , On the sixth day, part of the intestinal canal forms something like a loop (Figure 18, 20(5)), which is designated as the blind intestine (Figure 18, 20(8)}. When other parts of the digestive tract are already distinguishable to the naked eye, this loop thrusts out a little bit from the abdominal cavity (Figure 18, 21(7)). It is more clearly seen on the eleventh day, when the size of the intestines increases (62) (Figure 18, 22(12)). From the sixteenth day the loop starts to extend into the abdominal cavity, and this process ends by the nineteenth day. During this time all parts of the digestive canal acquire a defined shape.
This section of the dissertation ends with observations characteristic of the entire work.
EXTREMITIES OF THE WINGS AND LEGS. Tredern began by giving credit to Wolff, who had given the first and undoubtedly the best description of the early stages of development of the extremities. Tredern indicated that his own data were only a confirmation of Wolff's. Noting the different opinions of different authors concerning the time of appearance of the extremities (63) , Tredern gave the following description of their development. On the second and third days in that place where the extremities appear, cellular material accumulates. By the end of the second or the beginning of the third day, suddenly and perfectly distinctly, the foundation of the extremities appears, so that on the fourth day they have the shape of sacs (Figure 18, 3(9 - 10)) as though filled with a transparent material, in which no structure can be seen. On the fifth day, the central part of this foundation becomes whitish and much wider than before; there is a white cartilaginous material which is divided in separate parts. From the sixth day it is possible to see fingers, composed of this same transparent material, which cover the extremity in the form of a glove (Figure 18, 11(10 - 11)) C64) . A drawing illustrates the fingers of a goose embryo at the eighth day of incubation. In the chick embryo at the eighth day, the joints appear distinctly. On the tenth or eleventh day, the transparent material covering the fingers starts to move toward their tips, and something like the swimming web is formed, which on the twelfth and thirteenth days grows longer as the fingers grow. (Tigure 18, 14 - 16). The remains of this web then shortens (Figure 18, 18) . At this same time appear rudiments of the scales which will later cover the legs; the scales at the beginning are completely transparent. On the seventeenth day all the scales are finally formed, but so thinly that one can see all the vessels (Tigure 18, 17] through them. The posterior surface of the fingers is not covered by scales, but by something of a horny wart (Figure 18, 12(3), 18(4)). The claws are first apparent as of the eleventh or twelfth day. In this period they are straight and soft (Figure 18, 16(2)); later they gradually become curved, and on the sixteenth day they acquire their final form (Figure 18, 13). Only later do they enlarge and get harder (Figure 18, 18(1)).
In this section, Tredern suggested new facts and significant corrections to the descriptions given by previous erabryologists. Tredern 's poor optical facilities (he frequently points out that he made observations with his naked eye or with a lens) did not allow him to investigate the early stages of development or the more delicate structure of embryonic parts. In this respect he could not go beyond Wolff, whose name Tredern always mentioned with deep respect. Generally it is thought that Wolff's outstanding work on intestinal development was overlooked by his contemporaries and only rediscovered by Meckel. Even Baer, who knew Tredem's dissertation well, argued so. But it must be acknowledged that Tredern and not Meckel was the first to give credit to the classical work of that Russian academician. Tredern also considered mainly the later stages of chick development which had not been investigated prior to him. These related to the fate of the yolk intestinal duct, the development of the facial parts of the skull and beak, and the development of the extremities. Baer rightly noted that Tredern f s observations were repeated by other embryologists many years later.
Against the background of neglect for Tredem's work, his strict and serious study of the facts was readily overwhelmed by the attractive but unsubstantial fantasy of Naturphilosophie. Not without reason did the young Baer, feeling a decided hostility towards the influence of Naturphilosophie, become immediately fascinated by the small notebook of the unknown embryo logi st .
All knew and honored the great Baer; many remembered his fellow and direct predecessor, H. C, Pander. It is important to remember the name of that first embryologist of the nineteenth century, L. Tredern, who links Wolff and Baer in the history of Russian and world embryology. As the work of Wolff was apparently a model for Tredern and a stimulus to his continuation of research from the point at which Wolff had stopped, so Tredern' s humble work played a similar role as stimulus and model for Baer, though Baer surpassed that model significantly.
Cite this page: Hill, M.A. (2020, October 25) Embryology Book - Russian Embryology (1750 - 1850) 11. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_Russian_Embryology_(1750_-_1850)_11
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