22 EISEN. [Vol. XVII. 



or less distinct chromomeres, and that every such chromomere 

 possesses about six chromioles. This makes 432 chromioles in 

 all for the daughter-nucleus. 



When the nucleus of the following cell, the spermatocyte, 

 enters the metaphase we find the chromosomes in the shape of 

 split K's. The chromomeres in these are double and appear 

 to contain each six chromioles, or seventy-two for each chromo- 

 some. As there are twelve chromosomes, each equatorial plate 

 should contain 864 chromioles, which, after the equation-divi- 

 sion of the chromosomes, would again give to each daughter- 

 nucleus the same number as formerly, or 432 chromioles. 

 From this we are justified in assuming that during the conflu- 

 ent umbrella stage of the nucleus the chromioles have been 

 doubled. The easiest way to explain this increase is to assume 

 that each chromiole has been divided in two, thus presumably 

 preserving the quality while increasing the quantity. It is not 

 improbable that one of the objects of the confluent umbrella 

 stage is to allow the undisturbed division of the chromioles. 



The Chromoplasm. — By the chromoplasm I understand the 

 apparently homogeneous substance which directly surrounds 

 the chromioles during all stages of their existence, except, 

 perhaps, while they pass through the resting stage in the 

 polymorphous spermatogonia (Figs. 1-3). In this stage the 

 chromioles appear to lie free in a linin thread, at least there is 

 no visual evidence of their being surrounded by any chromo- 

 plasm. That each chromiole is actually surrounded by a thin 

 film of chromoplasm is, however, probable. As soon, however, 

 as the chromomeres are beginning to form, then we can see 

 that the individual chromioles are imbedded in a homogeneous 

 substance for which I propose the name " chromoplasm." It is 

 the chromoplasm which gives the chromosomes their general 

 form, appearance, and color. The chromoplasm constitutes 

 by far the greatest part of the chromosomes, and it appears to 

 be the vehicle for conveying and nourishing the chromioles. 

 As regards the want of chromoplasm in the polymorphous 

 nuclei, we may assume either that the chromoplasm has been 

 disintegrated or been used up as food for the chromioles, or we 

 may suppose that the chromoplasm has become concentrated in 



