THE RELATION BETWEEN AMITOSIS AND MITOSIS. 2O? 



stage of development from the spermatogonia to the developing 

 spermatozoa except during the spireme stage are subject to this 

 fate. The proportion of degenerating cell-groups varies greatly 

 in different chains, proglottids and testes. In some chains only 

 one or two cases of degeneration preceding the first appearance 

 of the spireme stage have been observed. In others degenerat- 

 ing groups are found in almost every testis in the spireme period. 

 During the earlier stages of the process the degenerating cells 

 form rounded masses : later these break up and become distrib- 

 uted through the testis and are apparently absorbed by the cyto- 

 plasm of other cells. While it is impossible to assign positively 

 a definite reason for this degeneration I am inclined to believe 

 that it results from differences in physiological condition which 

 may in turn be correlated with differences in nutrition. Careful 

 examination of regions of rapid growth in many forms often shows 

 a certain proportion of cells which are undergoing degeneration. 

 Undoubtedly in such regions the intensity of certain stimuli or 

 conditions carries some cells beyond the point where physiolog- 

 ical equilibrium can be regained and they degenerate, serving per- 

 haps as food for the others. There can be little doubt that the 

 testis is a region of this sort. The great variation in the fre- 

 quency of degeneration in different chains may indicate that it is 

 connected with nutritive conditions. Apparently more cells are 

 produced than can be sustained and some are eliminated. 



The fact that no case of degeneration beginning during the 

 spireme stage has been observed may be of some interest. It is 

 not improbable that this stage is relatively independent of external 

 conditions, i. e., that a cell having entered this stage is capable of 

 completing it without the intervention of external factors. To 

 judge from appearances this stage is a readjustment or the estab- 

 lishment of a new condition of equilibrium in the cell and it may 

 represent a reaction from previously existing conditions which 

 have disturbed the previous equilibrium of the cell. There can 

 be little doubt that in many respects the life of the cell possesses 

 a cyclical character. One complex of processes or reactions con- 

 tinues until it brings about a reversal in reaction or initiates a 

 different complex, etc. 



That this degeneration has any connection with amitosis is 



