62 EISEN. [Vol. XVII. 



somic process in arranging the chromosomes on the central 

 spindle and in pulling them apart. But the process takes no 

 active part in the formation of the chromosomes. 



The diromosovtic process again, as the name implies, refers 

 only to the nucleus and to the formation of chromomeres, 

 chromosomes, the splitting of the chromioles, and the manipu- 

 lation of the linin. The united object of the two processes is 

 to properly separate and divide the chromioles. The chromo- 

 somic process is presided over by the chromoplasts and the 

 linoplasts, just as the radiosomic process is presided over by 

 the archosome and the accessory archosomes. 



These two processes are carried through about seven gen- 

 erations of cells, four of which belong to the polymorphous 

 spermatogonia, and one each to the auxocytes, the spermato- 

 cytes, and the spermatids. These five classes of cells divide 

 according to three distinct kinds of mitosis : the polymorphous 

 spermatogonia by somatic or regular mitosis (not by amitotic 

 division), the auxocytes by heterotypic mitosis, the spermato- 

 cytes by homoeotypic mitosis. As regards the mitosis of the 

 spermatids I am uncertain, not yet having properly studied it. 

 I have, however, seen mitotic figures among the spermatids, 

 hence my supposition that we may possibly have among the sper- 

 matids two generations. Only the prophases of the somatic 

 mitosis will be treated of in detail in this paper. 



One of the most interesting parts of the chromosomic process 

 is the change of the mitosis with twenty-four chromosomes to 

 the mitosis with twelve chromosomes. This change seems 

 to take place in the imperfect resting stage of the auxocyte 

 and to be guided by the chromoplast. In the spermatogonia 

 the chromoplast projects finally twenty-four leaders, while in the 

 auxocytes the chromoplasts project finally only twelve leaders, 

 which latter change into chromosomes. As regards the reason 

 why this change is made and the particulars of how it is made, 

 we have no satisfactory observations upon which to base any 

 theories. Whether the reduction is the result of the chromo- 

 somic process alone, or the effect of a combination of the two 

 processes, is at present not quite clear ; there is, however, one 

 fact, that would seem to indicate that the radiosomic process, 



