6o EISEN. [Vol. XVII. 



Confluent Umbrella Stage. — The chromosomes and chromo- 

 plasts have become confluent (Figs. 104-107). Ring-shaped. 



Chrysanthetnum Stage. — A stage of the reappearance of the 

 chromosomes. During this stage the spermatids are separated 

 (Fig. 108), their arrangement being as the petals in a flower. 



The life cycle of the spermatocyte comprises thus a stage of 

 growth and a stage of mitosis. The stage of growth comprises 

 the chrysanthemum stage and the checkerboard stage, while 

 the stages of mitosis proper are the stages 3-9. 



Spermatids. 



The spermatid is the daughter-cell of the spermatocyte. It 

 is, even when full grown, considerably smaller than any of the 

 other cells. A study of the development of the spermatid 

 into the spermatozoon will be the subject of a future paper. 



VI. Mitosis. 

 A General Review of Mitosis. 



The mitosis of the cells of the testes of Batrachoseps is the 

 result of two independent parallel processes cooperating only at 

 certain points. For these two processes I propose the names 

 radiosoviic and chroniosotnic. 



The radiosomic process takes place in the cytoplasm of the 

 cell and does not directly affect the nucleus until the chromo- 

 somes have been formed ; the object of this process is to pre- 

 pare material for the rays or fibers, to evolve the mantle fibers 

 and the contractile fibers themselves, to destroy the nuclear 

 membrane and to form the central spindle. This radiosomic 

 process appears to be guided by the archosome and the acces- 

 sory archosomes. The radiosomic process continues after the 

 anaphase and consists then in creating the vacuole around the 

 nucleus by the means of a cytoplasmic membrane elevated 

 by fiber cones. The process ends with the formation of the 

 retractile fibers, the separation of the daughter-cells, and by 

 the dissolution of the fibers and the reconstitution of the 

 spheres. The radiosomic process cooperates with the chromo- 



