Januaby 1, 1915] 



SCIENCE 



tiation, regeneration, transplantation and 

 grafting; on the development of isolated 

 blastomeres and of egg-fragments; on the 

 symmetry and polarity of the egg; on the 

 relations of development to mechanical, 

 physical and chemical conditions in the en- 

 vironment; on isolated living cells and 

 tissues, cultivated like microorganisms, 

 outside the body in vitro; on fertilization, 

 artificial parthenogenesis and the chemical 

 physiology of development. In respect to 

 the extension of our real knowledge these 

 advances constitute an epoch-making gain 

 to biological science. And yet these same 

 researches afford a most interesting demon- 

 stration of how the remoter problems of 

 science, like distant mountain-peaks, seem 

 to recede before us even while our actual 

 knowledge is rapidly advancing. Thirty 

 years after Roux's pioneer researches we 

 find ourselves constrained to admit that in 

 spite of all that we have learned of devel- 

 opment the egg has not yet yielded up 

 its inmost secrets. I have referred to the 

 admirable discovery of Driesch concerning 

 the artificial production of twins. That 

 brilliant leader of embryologieal research 

 had in earlier years sought for an under- 

 standing of development along the lines of 

 the mechanistic or physico-chemical analy- 

 sis, assuming the egg to be essentially a 

 physico-chemical machine. He now ad- 

 mitted his failure and, becoming at last 

 convinced that the quest had from the 

 first been hopeless, threw all his energies 

 into an attempt to resuscitate the half ex- 

 tinct doctrines of vitalism and to found a 

 new philosophy of the organism. Thus the 

 embryologist, starting from a simple lab- 

 oratory 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. In- 

 stead he sometimes made himself a new 

 home — upon occasion even established him- 



self in the honored occupancy of a univer- 

 sity 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 towards the study of liv- 

 ing things. It is impossible not to admire 

 the keenness of analysis, and often the 

 artistic refinement of skill (which so capti- 

 vates us, for instance, in the work of M. 

 Bergson) with which the neo-vitalistie 

 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 h& 

 rudely shaken out of the ruts of our ac- 

 customed modes of thought by a challenge 

 that forces upon us the question whether 

 we really expect our scalpels and micro- 

 scopes, our salt-solutions, formulas and 

 tables of statistics, to tell the whole story 

 of living things. It is, of course, impos- 

 sible 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 con- 

 jured forth by modern vitalism are as ster- 

 ile 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 con- 

 science will sooner or later drive him back 

 into his 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 existence of an "elan vital," of "ente- 

 lechies," of "psychoids" be experimen- 

 tally verified? Even if beyond the reach 

 of verification may they still be of prac- 



