STUDIES ON CHROMOSOMES 355 



cases makes it certain that no fusion or process of disintegration 

 has taken place, nor is any evidence of a nuclear vacuole to be 

 seen. The chromosomes still retain the same form as in the pre- 

 ceding anaphases, the X F-bivalent lying near the center, and 

 still very clearly distinguished by its markedly bipartite form. A 

 very characteristic feature of this stage is the massing of mito- 

 chondrial granules on one side of the spindle-area as seen in side- 

 view (figs. 30, 31). This results from the fact that during the 

 division the chondriosomes are mainly massed around the spindle 

 and do not extend to any great extent into the polar areas (fig. 

 22). After completion of the division therefore the chondri- 

 somes still lie mainly on the side of the chromosome-plate. In a 

 general way this relation persists throughout the interkinesis. 

 In the condition just described the cells remain until the prophases 

 of the second division. It is probable that the interkinesis is of 

 rather brief duration, because in some cysts all stages may be 

 found between the closing anaphases of the first division and full 

 metaphases of the second. Cysts may, however, be found in 

 which practically all of the cells are in the condition described; 

 from which it may be inferred that a brief pause follows the com- 

 pletion of the first division. 



4. The second spermatocyte-division 



The prophases of the second division, which follow directly 

 upon the stage just described, are marked by a resumption of 

 activity on the part of the astral systems, which rapidly increase 

 in development while a definite spindle is formed between them. 

 As this takes place, the chromosomes spread further apart and 

 take up a position at the equator of the spindle in the same group- 

 ing as before. It is rather difficult to follow this change completely, 

 as these stages are not very abundant in my preparations, and 

 are almost always seen in oblique view. It is, however, certain 

 that a double movement of the chromosomes takes place, involv- 

 ing (1) a rotation of each chromosome through about 90 degrees, 

 so as to assume a position with its long axis parallel to the axis of 

 the spindle, and (2) a virtual rotation of the entire group, so as 



