96 EISEN. [Vol. XVII. 



near the new membrane forming between the two cells, their 

 function being to separate the two cells (Figs. 68-70). 



Ring Stage. — The last of the bretzel stage in which the 

 chromosomes are ring-shaped (Fig. 25, n.p.q.). 



Separated Segments. — The chromomeres and the segments 

 have separated, and the latter have twisted around each other, 

 and often cross each other in various directions (Figs. 16, 17). 



So7natic Mitosis. — Mitosis, with twenty-four chromosomes, 

 dividing in the same way as the somatic cells. The mitosis of 

 the polymorphous spermatogonia. 



SomospJiere. — The thin, dark-staining zone nearest surround- 

 ing the centriole, and situated interior to the centrosphere. It 

 has sometimes the form of a narrow, even band or thread. 



Spermatids. — The daughter-cells resulting from the mitosis 

 of the spermatocytes. Possibly two generations, the last of 

 which change directly into spermatozoa. 



Spermatocytes. — The second maturation cells. The daughter- 

 cells of the auxocytes. Mitosis homoeotypic and by equation 

 division, with twelve chromosomes. One generation only. 

 Chromosomes are placed on the spindle in the form of F's. 



Spindle Cones. — The cones formed of the retractile fibers 

 around the poles of the central spindle, when the latter has 

 been pulled through the ring-like nuclei of the daughter-cells 

 (Fig. 114). 



Spireme Segments or Leaders. — Strings of chromoplasm on 

 which are suspended the chromioles. There are as many 

 spireme segments as there are to be chromosomes. The spi- 

 reme segments do not form a single continuous thread, but are 

 individually separated. 



Umbrella Stage. — The chromosomes in the amphiaster or 

 anaphase have become confluent, and formed an umbrella-like 

 body, in which the individual chromosomes cannot be distin- 

 guished as such (Figs. 58-61). 



V-stage, in which the chromosomes have the shape of V's, 

 the apex of which is attached to the spindle. Includes a meta- 

 phase and an anaphase (Fig. 120). 



California Academy of Sciences, 



San Francisco, California, April 26, 1898. 



