The publication of Baer's projected textbook for some 

 reason did not take place. The possibility cannot be excluded 

 that Baer himself rejected this idea. Feeling the difficulty 

 of the great work related to a sphere of science to which he 

 was so close in the past, he was obliged to abandon it. 

 Actually, it was not easy after a ten-year interval, during 

 which Baer did not study embryology and did not follow the 

 literature of this topic, to coordinate all that had been 

 done by a complete galaxy of investigators — Rathke, Reichert, 

 Kolliker, Bischoff, and others — who had followed in his 

 footsteps, adding many new facts and raising new theoretical 

 questions. It was also necessary to take a definite position 

 coneming the cellular theory, which in the 1840s had spread 

 its influence to embryology. In addition to this, and even 

 in later years when Baer wrote his autobiography (i.e. in the 

 1860s), he did not consider it possible to speak decisively 

 concerning this theory. Recognizing the importance of that 

 wide biological generalization which the cellular theory 

 considered, Baer could not agree with the discrete presenta- 

 tion of the organism which was proposed by some supporters of 

 the cellular theory in the first period of its development, 

 and later in the era of Virchow and Schultze. 



However, Baer retained an interest in the problems of 

 the history of animal development. In 1845-46 he made an 

 attempt to return to research in embryology. Planning to 

 study the embryonic development of invertebrates, Baer 

 travelled to the Mediterranean coast and collected interest- 

 ing material in Genoa, Venice, and mainly in Trieste, which 

 consisted of fixed objects and drawings by an artist who 

 accompanied him. In this last attempt to return to embryo- 

 logical investigations, misfortune pursued Baer. Part of 

 the material was accidentally destroyed in Venice; another 

 part of it was lost elsewhere. 



But not all of the research carried out on the 

 Mediterranean coast could be considered fruitless (115). 

 The principal task of his trip to Genoa, Venice and Trieste, 

 as Baer wrote in his report, 13 was the study of the 



13. "Auszug aus einem Berichte des Akademikers v. Baer aus 

 Triest zom 1 (13) November 1845," BULL. PHYS.-MATH. 

 ACAD. SC. ST. PETERSB. (1847), 5, No. 15, pp. 231-240. 



(Contd. on next page) 

 466 



