by incubation the chick hatches from the egg if 

 nothing hinders that process . In this manner there 

 is a procession of essential forces; once they begin, 

 they continue and produce the gradual changes which 

 we see in time . ^ 7 



Thus, this progressive theory of developmental events 

 by essential causes, i.e. the epigenetic character of 

 individual development which was suggested, worked out and 

 defended by the establisher of the Russian and world 

 embryology K. F. Wolff, had gained the support of the 

 advanced materialistic philosophy of that time, as represented 

 by A. N. Radishchev. 



27. Ibid ., p. 99 

 140 



