THE PROGRESS OF SCIENCE. 



189 



form the essential arguments that he 

 had already put forward in more ex- 

 tended papers on the development of 

 fractional parts of the egg and on the 

 general problem of the localization of 

 morpliogenic processes, Driesch main- 

 tained that these processes have no 

 true analogue in the inorganic world, 

 are insoluble by any purely mechanical 

 or physico-chemical hypothesis, and 

 hence form a problem sui generis. The 

 most characteristic operations of the 

 living organism, more especially those 

 concerned in the processes of regenera- 

 tion, regiilation and the like, fail of 

 adequate interpretation on the so-called 

 'machine-theory' of life, and must be 

 regarded from a vitalistic as opposed to 

 a mechanistic standpoint. His con- 

 clusions, which were stated with great 

 lucidity and force, met with strong 

 opposition in the animated controversy 

 that followed, in which a number of 

 eminent embryologists participated. 

 Some of these speakers wholly denied 

 the validity of Driescli's reasoning and 

 endeavored to show that true analogues 

 to regulative phenomena occur in 

 purely physical processes. Others, 

 notably Professor Roux, took more 

 cautious ground, maintaining that de- 

 spite our present inability to explain 

 or even to conceive the nature of some 

 of the most striking and characteristic 

 phenomena of development, we are by 

 no means justified in taking refuge be- 

 hind such a word as 'vitalism,' which 

 carries with it so many misleading 

 connotations from the earlier period 

 when it was employed in connection 

 with the. exploded hypothesis of a 

 specific '\ital force.' 



The masterly and scholarly address 

 of Professor Biitschli, delivered before 

 the general session, contained not only 

 a specific examination of the main facts 

 in which Drieseh's position rests, but 

 also a critical study of more abstract 

 conceptions, such as those embodied in 

 the words 'mechanism,' 'causality' and 

 the like, which are inevitably involved 

 in the discussion of the subject. This 



address, whicli has been published in 

 pamphlet form by Engelmann of Leip- 

 zig under the title Mechanism and 

 Vitalism is worthy of attentive study, 

 not only by students of zoology, but 

 also by all who are interested in the 

 more general aspects of scientific prog- 

 ress. Recognizing the difficulties that 

 the mechanistic interpretation of 

 organic nature has to encounter, 

 Biitschli nevertheless expresses the 

 judgment that, in the broad sense of 

 the phrase, it is the only one under 

 which scientific investigation is pos- 

 sible, and that it is, to say the least, 

 wholly premature to speak of 'proofs 

 01 vitalism.' "The phenomena involved 

 in the localization process seem to me 

 not to differ fundamentally in kind 

 from those occurring in the inorganic 

 world." The acceptance of \italistic 

 hypothesis constitutes a backward step 

 in scientific method. "Both the old 

 and the new vitalism have done no 

 more than to emphasize the unsolved 

 riddles that confront us and to throw 

 doubt on the possibility of their ex- 

 planation on a mechanistic basis. The 

 assumption of vitalistic processes in- 

 volves the admission that they are ulti- 

 mate phenomena, in themselves inex- 

 plicable, that we are not able to sub- 

 sume imder general laws. Hence we 

 must take the ground that in vital 

 phenomena we can comprehend only 

 that which may receive a physico- 

 chemical explanation." How far the 

 mechanistic hypothesis will succeed in 

 the explanation of vital phenomena, 

 only the future will show. 'By their 

 fruits ye shall know them.' 



In considering the possibility of a 

 mechanistic explanation of the pur- 

 posive or teleological aspect of living 

 organisms Biitschli recognizes Dar- 

 win's theory of natural selection as the 

 sole fruitful attempt in this direction. 

 In view of the difficulties that have 

 been urged against that theory, and 

 especially the drastic criticism it has 

 received at the hands of some German 

 writers, it is interesting to find that 



