20 SCIENCE PROGRESS. 



attacked by a number of able workers, among others here 

 in London, by Dr. Starling of Guy's Hospital, who, by 

 sedulously studying the conditions under which the dis- 

 crepancies between the actual and the expected have arisen, 

 has succeeded in untying several knots. In reference to 

 the whole subject, it is to be noticed that the process by 

 which difficulties are brought into view is the same as that 

 by which they are eliminated. It is one and the same 

 method throughout, by which step by step, knowledge per- 

 fects itself — at one time by discovering errors, at another 

 by correcting them ; and if at certain stages in this pro- 

 gress difficulties seem insuperable, we can gain nothing by 

 calling in, even provisionally, the aid of any sort of Eidolon, 

 whether "cell," "protoplasm" or internal principle. 



It thus appears to be doubtful whether any of the 

 biological writers who have recently professed vitalistic 

 tendencies are in reality vitalists. The only exception 

 that I know is to be found in the writings of a well- 

 known morphologist, Dr. Hans Driesch, 1 who has been 

 led by his researches on what is now called the Me- 

 chanics of Evolution to revert to the fundamental con- 

 ception of vitalism, that the laws which govern vital 

 processes are not physical, but biological — that is, peculiar 

 to the living organism, and limited thereto in their 

 operation. Dr. Driesch's researches as to the modifi- 

 cations which can be produced by mechanical inter- 

 ference in the early stages of the process of ontogenesis 

 have enforced upon him considerations which he evidently 

 regards as new, though they are familiar enough to Physio- 

 logists. He recognises that although by the observation of 

 the successive stages in the ontogenetic process, one may 

 arrive at a perfect knowledge of the relation of these stages 

 to each other, this leaves the efficient causes of the develop- 

 ment unexplained [fukrt nicht zu einem Erkenntniss ihrer 

 bewirkenden Ursacheii)- — it does not teach us why one 



1 Driesch. " Entwicklungsmechanische Studien " : a series of ten 

 Papers, of which the first six appeared in the Zeitsch. /. w. Zoologie, vols, 

 liii. and lv. ; the rest in the Mittheihingen of the Naples Station. 



