The significance of the works of Wolff, who in fairness 

 is considered the founder of embryology as a science, can 

 scarcely be exaggerated. His advanced ideas about embryonic 

 development found favorable ground in the Petersburg Academy 

 of Science and received a practical base in the embryological 

 and teratological collections of the Kunstkamera. 



One of Wolff's most important services, as is known, is 

 the substantiation and the empirical proof of the epigenesis 

 principle. The establishment of the epigenetic character of 

 individual development made the existence of embryology as 

 a science possible, because the preformation theory predominat' 

 ing before disclaimed any qualitative change in the organism 

 from the ovum to the fully formed condition. The principle of 

 epigenesis as a study of the qualitative changes during the 

 individual life of the organism consequently set up the basis 

 of evolutionary, historical views of organic nature. 



In his lectures on general zoology, 19 K. F. Rule was 

 almost the first to connect the epigenesis principle with 

 an historical viewpoint. The following extracts are from 

 these lectures. "In nature, in the world of phenomena," Rule 

 wrote, "there is nothing that existed from the beginning; all 

 existing things are formed from non-existing things; all 

 the following are formed from repetitions of the foregoing 

 with the addition of the new; all is formed by constant slow 

 development (Epigenesis)" (p. 11). And later on: "In order to 

 understand how the animal is organized now, one must first 

 understand how it has been up to the present moment; its 

 formation in space becomes understood by appreciating its 

 origin in time. Zognosis is based on Zoogenesis" (p. 12). 

 "...all Zoogenesis is only an expression of the common fact 

 of genetic development: epigenesis directly opposes the 

 present view of investment of the embryo (Emboitement des 

 germes) or preexistence of the embryo (Preexistance des 

 germes), which was held by (Georges Cuvier) himself" 

 (pp. 12 - 13). In the following pages Rule gives brilliant 



19. K(arl) F(rantsovich) Rule (Charles Rouillier) , "Chteniya 

 ekstra-ordinarnogo professora Rule, 1850. Obshchaya 

 zoologiya" (Lectures of Extraordinary Professor Rule, 

 1850, General Zoology) (Litografir. izdanie) , pp. 11 f f . 

 The author has to thank S. R. Mikulinsky for indication 

 of this source. 



