PROFESSOR VIRCHOW AND EVOLUTION 439 



to be discovered, it is your bounden duty to search for 

 it," I should cordially agree with him. But by his un- 

 reserved denial he quenches the light of probability which 

 ought to guide the practice of the medical man. Both 

 here and in relation to the theory of evolution excess 

 upon one side has begotten excess upon the other. 



Note, — As might have been expected, Professor Yirchow shows himself 

 in practice far too sound a philosopher to be restricted by the canon laid down 

 in his critique of Dr. Haeckel. In his recent discourse upon the plague, he asks 

 and answers the question, "What is the contagium?" in the following words : 

 "Et qu'est-ce que le contagium? A mon avis, I'analogie de la peste avec le 

 charbon contagieux me paralt si grande qu'il me semble possible de trouver 

 un organisme microscopique qui contient le germe de I'affection. Mais jus- 

 qu'd present on a peu cherche k trouver cet organisme." — "Revue Soien- 

 tifique,*' March, 1879. 



