AMERICAN NATURALIST 



THE CONTEMPORARY EVOLUTION OF MAN. 



By Henry Fairfield Osborn. 



The Cartwright Lectures for 1892, No. L 1 



In the past decade of practical research and speculation in 

 biology two subjects have outstripped in interest and import- 

 ance the rapid progress all along the line. These are, first, the 

 life-history of the reproductive cell from its infancy in the 

 ovum onward, and second, the associated problem of heredity, 

 wdiich passes insensibly from the field of direct observation 

 into the region of pure speculation. 



As regards the cell it was generally believed that the nucleus 

 was an arcanum into the mysteries of which we could not far 

 penetrate ; but this belief has long been dispelled by the eager 

 specialist, and it is no exaggeration to say that we now know 

 more about the meaning of the nucleus than we did about the 

 entire cell a few years ago. At that time the current solution 

 of the heredity problem was a purely formal one; it came to 

 the main barrier, namely, the relation of heredity and evolu- 

 tion to the reproductive Veils, and leapt over it by the postulate 

 of Pangenesis. The germ-cell studies of Balfour, Van Bene- 

 den, the Hortwig brothers. Weisniann, Boveri and others have 

 gradually led us to hope that we shall some day trace the con- 



