270 KANSAS UNIVERSITY SCIENCE BULLETIN. 



separate into identical halves along the longitudinal split and 

 practically completes the movement by the time it enters the 

 spindle. No. 12 never seems to vary from this behavior. All 

 that remains to complete the division of No. 12 is separation of 

 the ends, and as soon as this occurs the chromatids spring 

 apart along the former longitudinal split and pass to the poles 

 as Vs. This is plainly seen, too, in a polar view of the second 

 spermatocyte (fig. 13a, chr. 12). This division is transverse 

 and consists of a separation of paternal and maternal elements 

 at the point of union during synapsis. 



In the first spermatocyte division the accessory passes un- 

 divided to one pole and as a consequence we get eleven chromo- 

 somes in one half of the second spermatocytes and twelve in 

 the other half (figs. 13, 14) . The distinctions between chromo- 

 somes made in the first spermatocyte can be carried out in the 

 second. The volume is of course reduced half (figs. 13a, 13b, 

 14a, 14b). The ring cannot be distinguished" by form, but its 

 size ranks it about 10. 



A comparison of figures 11, 12 and 13 will show the relative 

 size of the chromosomes of the first and second spermatocytes. 

 Figures 13 and 14 show the constancy in size and shape of the 

 chromosomes of the second spermatocyte. 



SUMMARY. 



1. The chromosomes of this complex form a graduated 

 series, the longest being nearly eight times the volume of the 

 smallest. 



2. All the chromosomes, with the exception of the accessory, 

 form true tetrads and divide longitudinally in the first and 

 transversely in the second spermatocyte. The accessory divides 

 longitudinally in the second spermatocyte. 



3. There are in this species no multiples or any other dif- 

 ferential chromosomes than the accessory, whose function and 

 history are so well known from the works of McClung and 

 others. 



4. At least five pairs of the chromosomes of this complex 

 can be recognized in the different cell generations. This com- 

 plex will be used as the basis for comparison in the other spe- 

 cies of this genus now under investigation.* 



* In justice to the author it should be stated that no opportunity was afforded 

 her to read the proof of this article. — C. E. M. 



