IS THE FIRST PRINCIPLES OF HEREDITY 



peated divisions (see Fig. 4, c) ; in the Alga Zanardinia 

 the two conjugating cells are already of widely divergent 

 character, approaching in type the bulky female and minute 

 active male germ. 



Further, that conjugation means more than mere fusion 

 and consequent separation of the cell-substance of the two 

 individuals concerned can be seen in those cases where, 



as in the Infusorian 



6 Paramaecium cau da- 



tum, an exchange of 

 nuclei can be clearly 

 demonstrated between 

 the two conjugating 

 animals. The two 

 bodies, after closely 

 approximating to each 

 other, send each a 

 nucleus across to the 



FIG. 1 1. -CONJUGATION OF ZANAR- other - Evidently the 

 DINIA. (After Reinke.) 



(From Delage, " H6r6dit6") 



a, female; b, male; c, conjugation; 

 d, product of conjugation. 



seems to be the mix- 

 ture and exchange of 

 the qualities of the two 

 parents and their re- 

 distribution among the offspring. We can, therefore, 

 regard this process as the last link leading up to real 

 "Amphimixis" i.e., the mixing of parental qualities for 

 the production of progeny. 



C. SEXUAL REPRODUCTION. 



It has become evident from what has gone before that 

 amphimixis, or the co-mingling of the sexes, is not the 

 essential element in the process of reproduction. Repro- 

 duction, which, as we have seen, can be carried on by a 

 single individual, and is only gradually delegated to two 

 differentiated sexes, has the one object that of the 



