CHAPTER 13 



THE DISCOVERY OF EMBRYONIC LAYERS: 

 THE DISSERTATION OF Kh. I. PANDER 



While Wolff's investigations represented an epoch in the 

 history of embryology, those works found considerable contin- 

 uity in the work of the Russian academicians Kh. I. Pander 

 and K. M. Baer. K. A. Timiryazev has emphasized Wolff's 

 significance for the second half of the eighteenth century 

 and Pander's and Baer's for the beginning of the nineteenth 

 century, in his brilliant essay on the history of biology. 

 He wrote that: 



Along with the static method of comparison in 

 the first years of the century, Karl Ernst von 

 Baer (and Pander) originated the "formative" 

 method, i.e. the investigation of the organism 

 in its sequence of developmental stages from 

 the ovum. Thereafter the wide study of the 

 history of development began. Here the word 

 "history" was used for the first time, not in 

 that undefined sense as in "natural history," 

 but in the strict sense of specifying the facts 

 in time and not in space. Embryology has grown 

 particularly in zoology, and the most remarkable 

 role has fallen to Russian zoologists (Baer and 

 Pander in the beginning of the century, and 

 Kovalevsky and Mechnikov in the second half) . 



Thus, the three stages of embryology are connected 

 with Wolff, then with Pander and Baer, and finally with 

 Kovalevsky and Mechnikov. As Timiryazev pointed out in 

 his familiar work, "The Historical Method in Biology," 



K. A. Timiryazev, "THE MAIN FEATURES OF THE 

 HISTORY OF DEVELOPMENT OF BIOLOGY IN THE 

 19TH CENTURY," INVESTIGATION, vol. 8 (1939), 

 p. 98. 



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