LIFE CYCLE OF SIMOCKIMI Al.irs VETULUS. 8l 



ferred to the brood pouch, I am con vi nerd that they are rrtaiiu-d 

 in it and that fertilization takes place after the egg is laid. 



VII. GENERAL DISCUSSION'. 



1. What relation does the presence of the males bear to the 

 origin and prolongation of the duration of the sexual state in 

 the females? 



One gets the impression from the literature that the ephippial 

 egg and ephippium are completely developed only if fecundation 

 occurs. Perhaps enough data have already been given in the 

 above discussion of the observations on pairing, of the effect of 

 the presence of males in prolonging the duration of the sexual 

 state of the females to convince any one that it is nil, though more 

 evidence is at hand. I wish to add here that I have observed 

 some hundreds of instances of embryo females developing through 

 the stage at which they would become sexual, if at all, which 

 never evinced the slightest evidence of sexuality. In a great 

 many instances these were in the same containers with sister 

 females which attained a high degree of sexuality. The males used 

 in some of these experiments were related to the females, but in 

 most instances they were not. It is evident that the ephippial 

 egg and the ephippium are both developed to within one or two 

 hours of the time of extrusion of the egg into the brood pouch, 

 in complete independence of the male, the only definite correla- 

 tions of these processes with the presence of males to be noted, 

 being that the egg is usually not laid in the absence of fecunda- 

 tion, the exceptions being, as I should judge, about i per cent, 

 to 5 per cent. I have observed about half a dozen instances. 



2. In the same environment are individuals which pass through 

 the sexual phase any more likely to give rise to males and sexual 

 females than are individuals which are parthenogenetic from the 

 beginning of their reproductive period? 



Since the twenty- fourth female in isolation experiment 3 

 gave rise to pure broods of males, pure broods of sexual females, 

 pure broods of asexual females, to mixed broods of males and 

 females, and to pure broods of females of diverse sexuality, thus 

 compassing the whole range of possibility as to kinds of offspring, 

 she was presumably normal, hence I used some of her sexual 



