THEORIES OF HEREDITY 117 



modification of the offspring should be similar to the 

 modification undergone by the parent. All the facts 

 known concerning the transformation of energy con- 

 tradict Spencer's statement, as mechanical energy can 

 be transformed into heat, heat into light, etc., etc. 



As far as physiological units are concerned, we hold 

 that those units do not possess from the mere fact of 

 their polarity (their only specific character, according 

 to Spencer) , the capacity of producing forms as com- 

 plex as living organisms. Moreover this theory only 

 solves the problem of heredity in so far as we concede 

 to the physiological units all the properties Spencer 

 attributes to them; and it solves the problem only in 

 the case of innate characters; the inheritance of ac- 

 quired characters remains unaccounted for, as the per- 

 sistence of force is not in itself a convincing argu- 

 ment. 



The conception of initial particles identical in their 

 nature has been the basis of many other theories. 

 Some attribute their properties to their geometrical 

 form, others to their motions (Haacke, Dolbear, 

 Haeckel, Cope) but this does not constitute a distinct 

 advance upon Spencer's theory, and in all those sys- 

 tems we find heredity explained in the same manner: 

 the offspring resembles the parent because it pro- 

 ceeds from a cell of the parent, and because the par- 

 ticles making up that cell (biological units, plasti- 

 duke, etc.) possess properties (polarity, mode of mo- 



