400 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1915. 



embryological research had in earlier years sought for an under- 

 standing of development along the lines of the mechanistic or 

 physico-chemical analysis, assuming the egg to be essentially a 

 physico-chemical machine. He now admitted his failure and, be- 

 coming at last convinced that the quest had from the first been hope- 

 less, threw all his energies into an attempt to resuscitate the half 

 extinct doctrines of vitalism and to found a new philosophy of the 

 organism. Thus the embryologist, starting from a simple laboratory 

 experiment, strayed further and further from his native land until 

 he found himself at last quite outside the pale of science. He did not 

 always return. Instead he sometimes made himself a new home — 

 upon occasion even established himself in the honored occupancy of 

 a university chair of philosophy. 



The theme that is here suggested tempts me to a digression, because 

 of the clear light in which it displays the attitude of modern biology 

 toward the study of living things. It is impossible not to admire the 

 keenness of analysis, and often the artistic refinement of skill (which 

 so captivates us, for instance, in the work of M. Bergson) with 

 which the neovitalistic writers have set forth their views. For my 

 part I am ready to go further, admitting freely that the position of 

 these writers may at bottom be well grounded. At any rate it is well 

 for us now and then to be rudely shaken out of the ruts of our 

 accustomed modes of thought by a challenge that forces upon us the 

 question whether we really expect our scalpels and microscopes, our 

 salt-solutions, formulas, and tables of statistics to tell the whole story 

 of li^dng things. It is, of course, impossible for us to assert that 

 they will. And yet the more we ponder the question the stronger 

 grows our conviction that the " entelechies " and such-like agencies 

 conjured forth by modern vitalism are as sterile for science as the 

 final causes of an earlier philosophy ; so that Bacon might have said 

 of the former as he did of the latter, that they are like the vestal 

 virgins — dedicated to God, and barren. We must not deal too 

 severely with the naturalist who now and then permits himself an 

 hour of dalliance with them. An uneasy conscience will sooner or 

 later drive him back into liis own straight and narrow way with 

 the insistent query: The specific vital agents, sui generis, that are 

 postulated by the vitalist — are they sober realities? Can the exist- 

 ence of an "elan vital," of "entelechies," of "psychoids" be experi- 

 mentally verified? Even if beyond the reach of verification may 

 they still be of practical use in our investigations on living things 

 or find their justification on larger grounds of scientific expediency? 

 However philosophy may answer, science can find but one reply. 

 The scientific method is the mechanistic method. The moment we 

 swerve from it by a single step we set foot in a foreign land where 

 a different idiom from ours is spoken. We have, it is true, no proof 



