CHROMOSOME GROUPS IN GALGULUS OCULATUS. 



299 



metaphase figures of the second division, without exception show 

 twenty chromosomes. Again I have counted the chromosomes, 

 in serial sections of the prophases before the nuclear membrane 

 breaks down. At this time, there are no granules within the 

 nucleus and several counts showed twenty chromosomes each. 





A 



W$$j£- 









B 





D 



♦«• 



• 



G 



Z • 



H 





Fig. 2. Galgulus oculatus. A and i?, metaphase figures of the second spermato- 

 cyte division, polar view, showing the ring of fifteen chromosomes and the pentad 

 group in the center — in B, the chromosome beneath the four group could not be 

 shown without displacing it ; Cand D, late anaphases of the second division, polar 

 view, showing the unequal distribution of the chromosomes ; E, side view of meta- 

 phase, second division, showing the typical arrangement and position of the pentad 

 group — the spindle in both E and F is diagrammatic and merely shows size rela- 

 tions ; F, side view of the early anaphase, second division, showing the manner in 

 which the chromosomes of the pentad group separate ; G, H and /, early anaphases 

 of the second division, showing the chromosome distribution to the two classes of 

 spermatozoa. All figures are drawn on the same scale and magnified 2,009 diameters. 



The second division, which follows immediately after the first, 

 shows a remarkable regrouping of certain of the chromosomes. 

 Fifteen of the twenty take up the position of a ring, within which 

 is a definite compound element formed by the remaining five. 



