GREATER PROBLEMS OF BIOLOGY THOMPSON. 381 



the problem of the origin of species, are indeed magnaiia natures; 

 and I take it that inquiry into these, deep and wide research specially 

 directed to the solution of these, is characteristic of the spirit of our 

 time and is the password of the younger generation of biologists. 



Interwoven with this high aim which is manifested in the biological 

 work of recent years is another tendency. It is the desire to bring 

 to bear upon our science, in greater measure than before, the methods 

 and results of the other sciences, both those that in the hierarchy of 

 knowledge are set above and below and those - that rank alongside 

 of our own. 



Before the great problems of which I have spoken the cleft be- 

 tween zoology and botany fades away, for the same problems are 

 common to the twin sciences. When the zoologist becomes a student 

 not of the dead but of the living, of the vital processes of the cell 

 rather than of the dry bones of the body, he becomes once more a 

 physiologist, and the gulf between these two disciplines disappears. 

 When he becomes a physiologist, he becomes, ipso facto, a student of 

 chemistry and of physics. Even mathematics has been pressed into 

 the service of the biologist, and the calculus of probabilities is not 

 the only branch of mathematics to which he may usefully appeal. 



The physiologist has long had as his distinguishing characteristic, 

 giving his craft a rank superior to the sister branch of morphology, 

 the fact that in his great field of work and in all the routine of his 

 experimental research, the methods of the physicist and the chemist, 

 the lessons of the anatomist, and the experience of the physician, are 

 inextricably blended in one common central field of investigation 

 and thought. But it is much more recently that the morphologist and 

 embryologist have made use of the method of experiment and of the 

 aid of the physical and chemical sciences — even of the teachings of 

 philosophy — all in order to probe into properties of the living organism 

 that men were wont to take for granted or to regard as beyond their 

 reach under a narrower interpretation of the business of the biologist. 

 Driesch and Loeb and Roux are three among many men who have 

 become eminent in this way in recent years, and their work we may 

 take as typical of methods and aims such as those of which I speak. 

 Driesch, both by careful experiment and by philosophic insight; 

 Loeb, by his conception of the dynamics of the cell and by his mar- 

 velous demonstrations of chemical and mechanical fertilization; 

 Roux, with his theory of autodetermination and by the labors of the 

 school of Entwickelungsmechanik which he has founded, have all in 

 various ways, and from more or less different points of view, helped 

 to reconstruct and readjust our ideas of the relations of embryological 

 processes, and hence of the phenomenon of life itself, on the one 

 hand, to physical causes (whether external to or latent in the mecha- 



