BIOLOGY OF PARACOPIDOSOMOPSIS. 45 



clearly individual chromosomes (Fig. 9). In the stages imme- 

 diately following this one, every phase in the reorganization of 

 the chromosomes is clearly demonstrable. In having a definite 

 resting stage between the abortive and the true division, Para- 

 copidosomopsis resembles Nenroterus (Doncaster, '09), but differs 

 from such forms as the bee and the wasp. 



After the cytoplasmic bud is cut off, the second spermatocyte 

 becomes spherical in outline, and a conspicuous maturation 

 spindle is formed (Fig. 12). The reorganized chromosomes are 

 drawn into the equatorial position on this spindle. Clear polar 

 views are difficult to find, owing to the fact that the chromosomes 

 are elongated and frequently twisted (Fig. 12). In the clearest 

 cases observed, the number of chromosomes is seen to be eight 

 (Figs. 10, n). 



The axis of the second maturation spindle bears no definite 

 relation to that of the first maturation spindle. This was deter- 

 mined by studying those second spermatocytes to which the 

 cytoplasmic bud remains for some time slightly attached. It 

 was found that the axis of the second spindle has no definite 

 relation to the point of attachment. 



In the second division the chromosomes split lengthwise, and 

 the daughter chromosomes pass to the opposite poles of the 

 spindle (Fig. 14). It is frequently easy to count the eight 

 daughter chromosomes passing to the one or the other of the 

 poles, but cells in which both daughter groups can be counted 

 are not often met with (Fig. 15). We conclude from these 

 observations that all of the chromosomes divide in the second 

 maturation. While in the anaphases the chromosomes are often 

 well scattered, yet we have found no evidence of a distinctly 

 "advancing" or "lagging" member, such as might indicate 

 that a particular chromosome had failed to divide. From this 

 it follows that the two spermatids resulting from the second 

 division will be alike. That is to say, the spermatozoa in 

 Paracopidosomopsis will not be dimorphic. 



In passing to the poles of the spindle the chromosomes keep 

 their long axes parallel to the long axis of the spindle (Figs. 

 15, 16), and upon reaching the pole fuse to form a solid, deeply 

 staining mass of chromatin out of which the spermatid nucleus 

 arises (Figs. 17, 18). 



