INFLUENCE OF A PREVIOUS IMPREGNATION. 275 



of a new individual, which may be accomplished in 

 other animals by a single copulation." * 



The repeated fertilization of the eggs of turtles is 

 apparently analogous to the phenomena observed in 

 the transmitted influence of a previous impregnation 

 to the offspring by a subsequent impregnation, as 

 pointed out by Agassiz in a lecture before the Massa- 

 chusetts Board of Agriculture in 1860 ; and he remarks 

 that his experiments with dogs, that have already been 

 mentioned, seem to show that " the impregnation of 

 an ovum may take place a long time previous to its 

 development, and that it probably only requires the 

 stimulus of future connections with a male to bring it 

 into existence." a 



In a subsequent lecture, in speaking of the influ- 

 ence of a previous impregnation upon offspring at a 

 later period, Agassiz says : " It therefore shows what 

 I have satisfied myself to be the truth among other 

 animals, by numerous experiments; that the act of 

 fecundation is not an act which is limited in its effect, 

 but that it is an act which affects the whole system, 

 the sexual system especially, and in the sexual system 

 the ovary to be impregnated hereafter is so modified 

 by the first act that later impregnations do not efface 

 that first impression." 3 



This is undoubtedly the most rational explanation 

 of the cases under consideration that has been pre- 

 sented, and there are additional facts which show that 

 the male element of fertilization may extend its influ- 



1 Loc. cit., p. 491. 



9 "Agricultural Report of Massachusetts," 1863, pp. 66, 57. 



'Ibid., 1856-V7, p. 84. 



