74 RISEN. [Vol. XVII. 



spindle. The F's are split and the mitosis is made by an equa- 

 tion division, the F's being exactly halved throughout their 

 length (Figs. 99-101). 



V-shaped AnapJiase. — The chromosomes are at the poles in 

 the form of contracting F's (Figs. 192, 193). 



Confluent Umbrella Stage. — The chromosomes have be- 

 come entirely confluent. This phase corresponds entirely to 

 the confluent umbrella phase of the auxocytes. It possesses 

 the same general characteristics as that phase, but there are no 

 fiber cones formed (at least not to the same extent as in that 

 phase, nor are they as plain or as pronounced, if they actually 

 exist). The same kind of cytoplasmic membrane is formed 

 around the nucleus which enters a reconstitution stage, just as 

 in the auxocytes. From a want of sufficient material this stage 

 has not been thoroughly studied (Figs. 104-108). 



Transition ChrysantJiemtmi Stage, in which the nucleus is 

 reconstituted through a stage of growth, the chromosomes 

 passing through a chrysanthemum stage into a checker- 

 board stage, as in the auxocyte. This is the last stage in 

 the life cycle of the spermatocyte and also the first stage of 

 the spermatid. As I expect to make the spermatids and their 

 evolution into spermatozoa the subject of a special paper, I 

 give here only a single figure of a perfectly formed spermatid 

 (Fig. 109). 



As regards the various stages of the chromosomic mitosis of 

 the auxocytes, I will only offer a few remarks. A. Bolles Lee 

 has recently described a stage in the mitosis of the spermato- 

 gonia of Helix pomatia, which he contends is new, and for 

 which he proposes the name " phase de I'eparpillement." Lee 

 supposes that the object of this stage is to prevent the two 

 halves of the same chromosome from being placed side by side in 

 the new nucleus. This "dispersion " stage is so similar to the 

 one that I have here described as the "separated segments" that 

 I have little hesitation in pronouncing them identical, and prob- 

 ably the object of the two phases is one and the same, not, 

 indeed, to disperse the chromosomes, but to enable the two 

 halves of a leader to separate sufficiently from each other dur- 

 ing the contraction process. However, not having seen the 



