108 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



is, at these times, in a very different condition from that in which it oc- 

 curs during cell rest. As I have already stated, from appearances noted 

 in the first spermatocyte (large type), the first change in the prophase 

 consists in the disintegration of the archoplasmic zone surrounding the 

 nucleus. The material becomes dispersed throughout the cell, causing 

 cytoplasm in all parts of the cell to stain in a uniform manner. This 

 change is due either to the solution of the archoplasm in the more fluid 

 hyaloplasm, or to its breaking up into invisible particles, which become 

 uniformly distributed. As a result of this process, the only visible evi- 

 dence at this time of the presence of archoplasm is furnished by the 

 slightly darker color of the hyaloplasm. 



Tins state of solution or dispersion is but a stage in the transformation 

 of the granular archoplasm of the resting stage into the fibrillar archo- 

 plasm of active mitosis. Convincing evidence of this fact is seen in the 

 early stages of mitosis in the various cells. The growth of the astral 

 rays of the first spermatocyte, huge type, advances from the centrosome 

 outward. As the archoplasm in solution is converted into astral rays the 

 inter-reticular portions pari passu stain less deeply, and thus assume 

 the appearance characteristic of hyaloplasm. This is especially notice- 

 able during the rotation of the spindle. The astral rays when first 

 formed in the early metaphase involve only the third of the cell nearest 

 the spindle. The hyaloplasmic areas of this portion of the cell thus 

 become transparent, while those in the ends of the cell where the astral 

 rays have not as yet penetrated still show the deeper stain characteristic 

 of the early prophase. By the rotation of the spindle the centrosomes 

 come into closer relation with these end regions, so that in the early ana- 

 phase all parts of the cell are penetrated by astral rays. Meanwhile the 

 inter-reticular areas in all regions have lost their contained archoplasm 

 and are transparent. Stages in this transformation have been repre- 

 sented in Figures 32-35 (Plate 3) and 144 (Plate 8). 



The prophase of the first spermatocytes of the small type likewise 

 affords evidence that the archoplasm undergoes a kind of solution while 

 being transformed into astral rays. In the small cells the archoplasm is 

 not, as in the large spermatocytes, distributed throughout the entire cell 

 at the beginning of the prophase, but collects at one side of the nucleus 

 in a granular mass. This condition continues until the chromosomes 

 have become quite dense. The next change occurs when the centrosome 

 migrates to the nuclear membrane. At this time, and during the later 

 separation of the centrosomes, the archoplasm gradually becomes dis- 

 solved and converted into astral rays. It is not all dissolved at once, as 



