504 



arrangement at this time, one ordinarily sees an irregular peripheral 

 band of twelve or thirteen chromosomes with the others, which are 

 smaller, inside. Not infrequently, however, from one to three may lie 

 outside the general band, sometimes at considerable distance from it, 

 in which case one is commonly larger than the others and judging 

 from its deeper color and irregular shape, may be the odd chromo- 

 some, although the indications were not sufficiently marked to positi- 

 vely establish its identity. 



The smaller outlying chromosomes, on the contrary, stain less 

 intensely or else decolorize more rapidly so that instead of the bluish 

 black of the ordinary chromosome they are of brownish yellow color 

 when stained with iron haematoxylin. Whether this less intense color 

 indicates a constitutional peculiarity of these particular chromosomes 

 or whether it is simply due to their smaller size and their more 

 isolated position in the cell could not be determined. 



In some instances a side view of the spindle of the dividing 

 spermatogonium shows the chromosomes strung across the field in 

 different degrees of approximation to the poles. A pair of small round 

 chromosomes not infrequently are the first to lead off in division as 

 shown in Fig. 2, and they may be followed at irregular intervals by 

 others. This would indicate that the individual chromosomes divide 

 and separate independently one of another. The halves of each pair, 

 indeed, seem at times to diverge at more or less independent rates. 



One or two plasmosomes were to be seen in some preparations 

 but no definite and constant relation to any individual chromosomes 

 was traceable except that in several instances one or two small chromo- 

 somes were seen in a plasmosome or sometimes, in the case of two, 

 on each side of it. 



During the ensuing period of growth and development whereby 

 the products of the spermatogonial divisions become primary spermato- 

 cytes the ordinary course of events is not essentially different from 

 that which is found in the pigeon. 



Usually two and often three chromatic bodies or chromatin nu- 

 cleoli persist throughout this period. When three are present, one of 

 them is more or less irregular in shape and is considerably larger 

 than the others which are always small and usually round. From the 

 fact that the former may take on the curved or comma shape charac- 

 teristic of the odd chromosome, one is inclined to believe that it is 

 in fact this body although under these conditions considerably smaller 

 than at the periods of mitosis. Fig. 4 is a camera lucida drawing of 

 the nucleus and the adjacent sphere substance during the open spireme 



