20 EISEN. [Vol. XVII. 



chromosomes begin to reappear from the confluent umbrella, 

 the chromioles appear at once and as well defined as ever. We 

 therefore must assume either that during the confluent stage 

 the chromioles do not stain sufficiently to be distinct one from 

 the other or from the chromoplasm surrounding them, or that 

 those globules which are observed there are actually the chro- 

 mioles, though less regularly arranged. 



In all previous stages of chromosomic evolution the chromi- 

 oles are distinct in almost every chromosome, and, as I have 

 said, may in favorable instances be counted. Beginning with 

 the resting stage of the nucleus of the polymorphous spermato- 

 gonia, we find that the chromioles are the only parts of the 

 chromosomes which are distinctly visible or regularly organ- 

 ized. In this stage the chromioles are not united into chro- 

 momeres and chromosomes, but occur free in the nucleus and 

 separated from each other and only connected by a thread of 

 linin. They do not even appear to be surrounded by the usual 

 covering of chromoplasm, but are, so to say, strung one after 

 the other on linin strings, which latter apparently run in the 

 same general direction (Figs. 1-3). 



In a somewhat later stage several, or from two to three, 

 chromioles are seen to congregate together and form the 

 beginning of a chromomere, as, for instance, in Figs. 4, 5, 

 etc. In a later stage the chromomeres are yet more dis- 

 tinct and they are then seen each to contain three chromi- 

 oles, situated very close together and surrounded by a thin 

 film of lighter staining chromoplasm (Figs. 12-14). When 

 again at a later stage the chromomeres have been perfectly 

 formed, we find that each chromomere contains six chromioles 

 and the supposition lies near at hand that each individual 

 chromiole has divided in two (Fig. 15). The chromioles are 

 now so arranged that three and three are on each side of the 

 chromomere, there appearing between them a lighter staining 

 line which may be followed all through the leader or spireme 

 segment. When this segment splits in the next stage the 

 splitting is carried along this line, and the newly split half will 

 thus only possess three chromioles in each split chromomere. 

 But when at a later stage the chromomeres have formed into 



