Evolution of Sex 355 



nucleus and cytoplasm and centrosome; which consists in 

 some disturbance of the chemical affinities. The centrosome 

 persistently dividing as before, and carrying with it the 

 nuclear divisions, fails to divide the cytoplasm, which is in 

 this case an abnormally large mass of the cell ; and so a divi- 

 sion occurs, sometimes stimulated by the male cell, wherein 

 the half nucleus leaves the parent cell stripped of all mass; 

 a mere fragment denuded. Then the half which remains, 

 still a duplex nucleus, splits into single elements, and one 

 group of these single chromosomes is also ejected, while 

 simultaneously the last duplex spore ejected splits into two 

 singly constituted spores. Thus the abnormal great cell 

 stands with single chromosomes; after producing three 

 spore cells resembling those of the exhausted cell. It would 

 seem that in both cases the dividing act is due to a loss of 

 chemical affinity between the centrosome nucleus and cyto- 

 plasm, but in the small cell the cytoplasm has lost its ener- 

 getic character (perhaps alkalinity) while in the large cell it 

 seems to be the nucleus which is changed (having lost per- 

 haps active acidity). This inference is in harmony with the 

 facts that follow. We have seen that the escaped nuclei 

 of the small cell became errant or motile. Sometimes be- 

 cause of mere infinitesimal size, sometimes by use of actual 

 cilia or motile organs, they wander from the old placement ; 

 and when they arrive in the vicinity of a great cell, as some 

 do, there appears an attraction which is very different from 

 the older conjugating force. They unite with a more in- 

 tense activity, not merely to add their heredity in a common 

 fund and produce a cell capable of simple division, but to 

 renew the vital functions of the whole historic nucleus, and 



