CELL-LIFE AND CELL-MULTIPLICATION. 267 



organs in plants at times when, and in places where, shoots 

 are falling off in vigour and leaves in size. Here the suc- 

 cessive foliar organs, decreasingly fitted alike in quality and 

 dimensions for carrying on their normal lives, show us an 

 approaching cessation of asexual multiplication, ending in 

 the aborted individuals we call stamens; and the fact that 

 sudden increase of nutrition while gamogenesis is being 

 thus initiated, causes resumption of agamogenesis, shows 

 that the gamogenesis is consequent upon the failing 

 agamogenesis. See then the parallel. On going back 

 from multicellular organisms to unicellular organisms (or 

 those homologues of them which form the reproductive 

 agents in multicellular organisms), we find the same law 

 hold. The polar bodies are aborted cells, indicating that 

 asexual multiplication can no longer go on, and that the 

 conditions leading to sexual multiplication have arisen. If 

 this be so, decrease in the chromatin becomes an initial 

 cause of the change instead of an accompanying incident; 

 and we need no longer assume that a quantity of precious 

 matter is lost, not by passive incapacity, but by active expul- 

 sion. Another anomaly disappears. If from the germ-cell 

 there takes place this extrusion of superfluous chromatin, the 

 implication would seem to be that a parallel extrusion takes 

 place from the sperm-cell. But this is not true. In the 

 sperm-cell there occurs just that failure in the production of 

 chromatin which, according to the hypothesis above sketched 

 out, is to be expected; for, in the process of cell-multiplica- 

 tion, the cells which become spermatozoa are left with half 

 the number of chromosomes possessed by preceding cells: 

 there is actually that impoverishment and declining vigour 

 here suggested as the antecedent of fertilization. It needs 

 only to imagine the ovum and the polar body to be alike in 

 size, to see the parallelism ; and to see that obscuration of it 

 arises from the accumulation of cytoplasm in the ovum. 



A test fact remains. Sometimes the first polar body ex- 

 truded undergoes fission while the second is being formed. 



