HISTORY OF WOLFF. 43 



mindedness of the professors of the Berlin Medico-surgical 

 College, who were averse to all scientific progress. This 

 most learned faculty persecuted the Theory of Epigenesis 

 as one of the most dangerous heresies ; just as is the case 

 now with the Theory of Descent. Although Cothenius, 

 and other patrons in Berlin, took a warm interest in Wolff, 

 it was impossible even to procure permission for him to 

 give public lectures on Physiology in Berlin. The conse- 

 quence was, that Wolff was obliged to accept a summons 

 with which the Empress Catherine of Russia honoured him 

 in 1766. He went to St. Petersburg, where he remained 

 for twenty-seven years, devoting himself in undisturbed 

 quiet to his deep researches, and enriching the publications 

 of the St. Petersburg Academy with the productions of his 

 brilliant talents. He died there in 1794. 19 



The progress which Wolff made in the entire science of 

 Biology was so great that the naturalists of that time could 

 not grasp it. The mass of important new researches, and 

 of fruitful and great ideas accumulated in his publications, 

 is so enormous that their full value has only been gradually 

 appreciated, and their bearing properly understood during 

 the present century. Wolff opened up the right path into 

 the most various branches of biological investigations. 

 Firstly, and above all, by the Theory of Epigenesis, he 

 first made the real nature of organic evolution intelligible. 

 He proved satisfactorily that the evolution of every organ- 

 ism consists of a series of new formations, and that no 

 trace of the form of the developed organism exists either in 

 the egg or in the semen of the male. These are simple 

 bodies of an entirely different significance. The germ, or 

 embryo which develops from the egg, shows in the various 



