EFFECT OF CONJUGATION 361 



ready to conjugate (as were the non-conjugants in most of our 

 experiments). Such spht pairs could not be had in the present 

 case. Of the six conjugant Unes, four (or 66 per cent) died out; 

 but of the non-conjugant Hnes all died. 



As set forth in the account of this experiment, the ground for 

 this difference seems to lie in the fact that a certain vigor and 

 power of multiplication are a prerequisite for conjugation; so 

 that in the only three pairs that conjugated are included the only 

 vigorous members of the stock; the others died for the same reason 

 that they did not conjugate. 



Wliat are the grounds for the greater mortality of the conju- 

 gants, found in the great majority of cases? Two possible 

 grounds occur to one : 



1. Conjugation involves extremely complex and delicate cyto- 

 logical processes. It seems possible that these processes are 

 easily diverted into abnormal courses, resulting in abnormalities 

 and death. 



2. Conjugation, like fertilization, is a process of uniting diverse 

 germ plasms; of producing new combinations of germ plasm 

 (evidence bearing directly on this will be given in a paper to 

 follow the present one). Possibly some of these combinations 

 are incompatible; or produce results not fitted for continued 

 existence under the conditions. 



EFFECT OF CONJUGATION ON ABNORMALITIES 



Throughout the experiments it was observed that frequent 

 abnormalities of all sorts occur among the descendants of the 

 conjugants, while among the descendants of non-conjugants 

 such are relatively rare. The grounds just set forth as possibly 

 accounting for the greater death rate of the conjugants, perhaps 

 play a part also in the production of abnormaUties. 



EFFECT OF CONJUGATION ON VARIATION 



The most striking effect of conjugation that appears in com- 

 paring the conjugants and non-conjugants, is the great increase 

 in variability in the rate of reproduction. In all of the experi- 

 ments the conjugants are much more variable in this respect than 



