134 MARINE BIOLOGICAL LABORATORY. 



and ancestral traits, and does not accord with the facts 

 of the early appearance and isolation of apparently com- 

 plete germ cells. Moreover Galton's well known experi- 

 ment of the transfusion of the blood of eighteen silver- 

 gray rabbits with that of other varieties showed that the 

 gemmules, if existent, do not circulate in the blood, for 

 this transfusion of blood was not accompanied by the 

 slightest interchange of characteristics. 



Passing by Haeckel's suggestion of Perigejtesis, which 

 invests the molecules of organized matter with some of 

 the lower faculties of mind,i let us look at Brooks's in- 

 genious attempt to modify Darwin's hypothesis. His 

 postulates were the actual existence of the gemmules, 

 but not quite as conceived of by Darwin, for there is a 

 fundamental difference between the male and female 

 elements of reproduction. The ovum is conservative, 

 reproducing cells like itself and a storehouse of heredi- 

 tary tendencies, giving rise directly to new ova, while the 

 spermatozoan is the progressive element, the repository 

 of the gemmules. Nor are the gemmules thrown off at 

 random by all the cells of the male body, but especially 

 by those which are disturbed in their conditions by a 

 change in environment. Variability, therefore, is most 

 rapid when external conditions are disturbed, and it 

 springs from the union of the ovum and spermatozoan. 

 This system is open to most of the objections which can 

 be raised against the original of Darwin, but is moreover 

 opposed by the rapidly accumulating evidence for the 

 essential similarity of the ovum and spermatozoan. 



1 See Brooks's Heredity, p. 37. " Unconscious memory is the most 

 important characteristic of organized matter. Heredity is the memory of 

 the plastidules; variability, their power of perception." 



