He introduced controversy only on occasions of utmost importance 

 Then he disputed the opinion of only the most authoritative 

 investigators, such as Wolff and Pander. "To object to work 

 which disappears quickly without any trace is entirely useles 

 . . . ," he wrote. "If it comes to frequently returning to 

 any such work, confirming it or, on the contrary, disputing 

 it, this only indicates the importance of this work." 



Turning to the drawings accompanying his work, Baer 

 remarked on the difficulty of combining in them documentary 

 accuracy and clarity, and he confessed that he could not 

 completely achieve such a combination. In difficult cases 

 he sacrificed accuracy in favor of clarity. At that time, 

 the difficulty of understanding the still very insufficiently 

 investigated ideas of embryological development required clear, 

 schematized illustrations. 



In the conclusion to his preface, Baer justified including 

 in his work a special section devoted to general subjects and 

 representing a statement of his scientific belief in the 

 history of animal development. The objective of publishing 

 these general views was an attempt to promot other investigators 

 to make more detailed studies of embryological problems. Even 

 of Oken's fantastic ideas, Baer wrote: "Regardless of the fact 

 that many of them now should be considered wrong, they have 

 invaluably affected the history of development, because they 

 led naturalists to a clearer understanding of the question. "^ 



Possibly, more detailed study is no less important than 

 achieving generality, especially for the earliest stages of 

 development, Baer suggested. Thus: 



That an understanding for the first days of 

 development still lacks something, . . . you 

 will at least suspect. And whoever remains 

 in this difficult field, in which each branch 

 seeks to be individual and carefully united, 

 does not achieve all even if he tries hard 

 all his life for the harvest; and who would 

 not take away empty ears of corn for full 

 ones? Kaspar Friedrich Wolff, who truly 



5. (I, xvii-xviii) 

 304 



