142 KANSAS UNIVERSITY QUARTERLY. 



the chromosomes are grouped about their respective centrosomes, and 

 the connecting fibers traverse about the same ellipsoidal course as did 

 the fibers of the raetaphase. The absence of granular cytoplasm in 

 this case is probably accidental. 



At this point I again find a gap in the series, the next stage repre- 

 sented being a cyst containing two cells in the stage shown in fig. 13, 

 /. e.. cells whose nuclei are composed of a number of pockets contain- 

 ing chromatin in a diffused condition. This is the phase which I 

 have designated as l)etween telophase and prophase. The two cells 

 of this stage and generation which I did find, however, differed from 

 cells of the same stage in later generations in no essential particulars. 

 They did not show the accessory chromosome nor did the few cells of 

 the second generation which I was able to find, probably on account 

 of the position of the element in the cell. It is therefore impossible 

 to state whether this interesting structure appears in the first or in a 

 slightly later division. There is, however, only one explanation for 

 the partitioned or lobulated condition of the nucleus, and that is the 

 course which brings about the same condition in later generations. 

 Briefly, it is this : Immediately after the formation of the partition 

 wall between the daughter-cells, the chromosomes begin to disinte- 

 grate. They lose their homogeneous appearance and become granular, 

 and, at the same time, there is formed about each one a distinct mem- 

 brane. (A cross-section of such a cell is shown in fig. 12.) This con- 

 diticjn of separate chromosomic vesicles, however, does not last long, 

 as the partition walls between them are soon dissolved where they 

 come in contact with each other at their polar ends, so as to produce 

 the iDeculiar glove -like effect of fig. 30. 



The condition of fig. 13, which represents a cross-section of the 

 "fingers" of the "glove," is then reached by a simple separation of 

 the chromomeres. 



THE SECONDARY SPERMATOGONIA. 



When, in the telophase of the transformation division of a primary 

 spermatogonium, the chromatin has reached the utmost limit of diffu- 

 sion, it begins to take on the form of an extremely fine convoluted or 

 spiral thread in each of the diverticula of the nucleus. 



This is the first of the prophases of the secondary siDermatogonia 

 as well as the Vx'giuning of a cyst, for a common membrane may now 

 be seen about these tw^o cells, which envelops their descendants 

 throughout their divisions and marks them off from other cysts. 



There are, however, a few cases in my preparations which seem to 

 be exceptions to this rule. Although it is almost invariably the case 

 that all the cells of a cyst are in the same, or very nearly the same, 

 stage of development, occasionally a small cyst is found which shows 



