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[N. S. Vol. XXXIV. No. 864 



mind would like to have an answer, if pos- 

 sible; it is one which many contemporary 

 biologists (though chiefly thi-ough vaguely 

 confusing it with other questions) suppose 

 they have conclusively answered, in the one 

 way or the other; and it is one upon which 

 light may conceivably be thrown by the prog- 

 ress of experimental inquiry duly conjoined 

 with logical analysis. 



3. There is, as I have previously pointed 

 out, another theory going under the name of 

 vitalism which asserts organic autonomy, but 

 also something more. It is the doctrine that 

 certain vital phenomena are not dependent 

 upon " any fixed configuration of material 

 parts existing in the organism or cell at the 

 moments at which the phenomena take place " 

 — i. e., that the same phenomena occur in a 

 given organism in spite of profound modifica- 

 tions of the composition and configuration of 

 the parts, through a sort of redivision of 

 labor and redistribution of functions among 

 the parts that remain. This doctrine is the 

 ' substance of the conclusion which is sug- 

 gested by Driesch's analysis of what is im- 

 plied by the totipotency of parts in certain 

 cases of morphogenesis, and by regeneration- 

 processes." This view seems to Professor 



" It was to this doetrine alone that I referred in 

 the passage upon which Professor Jennings com- 

 ments at p. 931, note 12; I was not, as I supposed 

 the context made clear, attempting a summary of 

 Driesch's whole system. But I appear to have 

 expressed myself ambiguously, and am glad, 

 therefore, to have Jennings call attention to the 

 fact that Driesch's theory is ''not limited to 

 morphogenesis. ' ' It is, however, true that the 

 most distinctive and novel thing in that biolo- 

 gist's doctrine is his conception of "harmonious 

 equipotential systems " ; as he himself declares, 

 what is really characteristic in neo-vitalism is due 

 "to the renaissance of experimental morpholog- 

 ical inquiry, to the ' Bntwieklungsmechanik ' of 

 Wilhelm Eoux; all the new factual evidence for 

 the doctrine of Lebensautonoviie has been found 

 in this field" (DerVitalismus, 1905, p. 155). For 

 a discussion of the import of Driesch 's arguments 

 from behavior, and their relation to his argu- 

 ments from morphogenesis, space is lacking here. 

 Though I think Jennings misconceives Driesch's 

 position in ascribing to him a wholesale ' ' experi- 



Jennings tantamount to biological indeter- 

 minism and to a denial (so far as it reaches) 

 of the principle of uniform causality. It is 

 equivalent to an " admission that the prin- 

 ciple on which experimental investigation is 

 based breaks down when applied to biology." 

 A closer scrutiny of the doctrine's implica- 

 tions will, I think, disclose in it no such 

 anarchical propensities. All that it logically 

 need imply may be stated as follows : Within 

 certain limits, at least some organisms are 

 capable of realizing or maintaining the typical 

 form of their species in spite of profound ex- 

 ternally caused quantitative or qualitative 

 changes in their physico-chemical mechanism; 

 so that the "prospective potency" (at a given 

 moment) of any single component particle is 

 not a function of its own chemical nature 

 plus the number and chemical nature of the 

 other particles, but can be predicted only by 

 means of a knowledge of the typical form of 

 the species. But that typical form itself is a 

 constant function of an original chemical 

 compound of a specific type, viz., the fertilized 

 egg of the given species. Hence, given the egg 

 (or in the case of regeneration, the adult form) 

 of a determinate species, everything about the 

 process occurs in a regular, law-observing and 

 experimentally investigable manner; only, one 

 of the laws to be borne in mind is the law 

 that the typical form of the species gets itself 

 realized despite the radical mutilation of the 

 mechanism and hy means of a radical internal 

 readjiistment of the mechanism. There need 

 in this be nothing arbitrary, nothing to baffle 

 the purposes of the experimenter. It is open 

 to him to ascertain by his usual methods how 

 far, in a given organism, the morphogenetic 

 units are " equipotential " ; what are the lim- 

 iting conditions of the organism's ability to 

 maintain its typical form by the use of di- 

 verse internal ■ mechanisms ; and what are the 

 steps of physical and chemical change by 

 which the redistribution of functions and 

 restoration of structure get accomplished. A 

 " machine," for Driesch, is any system, each 



mental indeterminism, " I do not wish to compli- 

 cate the discussion with exegetical inquiries into 

 the precise meaning of a rather difficult writer. 



