502 SCIENCE PROGRESS. 



the charge of implying the existence of minute parts each 

 of which already possesses the essential characters of the 

 body which are to result from their agency. 



As to such hypothetical, material particles, Mr. Bourne 

 has justly urged that when we try and get, by the aid of 

 the imagination, behind and beyond what is perceptible to 

 the senses, we become the victims of mere mental images, 

 which he, after Wolff, terms f abides. 



Hypothetical " gemmules," " plastidules," "micellae," 

 "inotagmata," " idiosomes," "plasms," etc. (however prac- 

 tically useful as working hypotheses), each and all, he tells 

 us, when carefully considered, will be found no less to need 

 explanation themselves than do the phenomena they are 

 called in to explain. Such is the case since the "difficulty 

 as regards vital phenomena" is not "in any way dimin- 

 ished " by their aid, but " simply moved further back ". As 

 to Professor Weismann's " biophors," he remarks, 1 they 

 exhibit the primary vital forces, assimilation and meta- 

 bolism, growth and multiplication by "fission," while "they 

 are also bearers of the qualities of cells " and have " heritable 

 qualities " which they can hand on to their progeny. 2 

 Again, he adds: 3 "Whitman must have his idiosomes to 

 explain what he found inexplicable in cells, but what 

 explains the behaviour of idiosomes ? " Yet Mr. Bourne 

 himself shows a favour to "molecules," which he denies to 

 imaginary entities of supposed larger dimensions. He tells 

 us: 4 "We may concede a great complexity of molecular 

 structure to the idioplasm of the nucleus ". Of course we 

 may ; but what then ? 



1 P- JI 3- 



2 According to Weismann each biophor is also capable of changes and 

 modifications by means of rearrangements of its constituent molecules. 

 Now such changes and modifications cannot be uncaused but must be 

 induced in the biophor during its life by its environment. But the char- 

 acters of the biophor are heritable. Therefore, the biophor is a living 

 creature, which is capable of transmitting acquired characters to its pos- 

 terity. This is surely no small argument um ad hominem in favour of their 

 transmission by organisms, of which the biophor is but a diminutive 

 representative ! 



3 p. 124. 4 p. 125. 



