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 



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