LINKAGE OF CHROMOSOMES. 167 



The same kind of division evidently takes place in the V-multiple 

 here. In Fig. 52, we can see the one V going over to one pole a 

 little after the other chromosomes have passed. What appears 

 to be the other half of the V has already reached the opposite 

 pole. I did not find another cell showing this conclusively 

 but the division of the other parts of the chromatin matter would 

 seem to indicate this interpretation. The V at the pole is 

 again the size of the multiple in the spermatogonial stage. 



Jamaicana unicolor Brunner. 



The two individuals of /. unicolor differ. One is of the simple 

 rod type, while the other shows the two V-chromosomes. 



The spermatogonial metaphase figures of individual 430.1 

 show thirty-five chromosomes of the rod type (Figs. 54-57). 

 There is nothing in their appearance or behavior to distinguish 

 them from individual 589 of /. flava or from individuals 416, 

 585, 586, 587 and 438 of /. subguttata and the same holds true 

 in later stages of growth. 



In No. 560.1, the second individual of this species, I found 

 two multiple chromosomes (Figs. 58-67). In addition to the 

 thirty rod autosomes, the accessory and two large V's are to be 

 seen on the periphery of the spermatogonial metaphase figures. 

 The chromatin material in this series of slides is so badly massed 

 that perfect cells are difficult to find. For this reason I can not 

 be certain of the size relations among all the chromosomes but 

 I have gained the essential facts for my purpose. The largest 

 chromosomes are quite clear and distinct so that I can number 

 the mates of the five largest pairs besides the accessory. Figs. 

 58-60 show the number and arrangement of the chromosomes. 

 Many spermatogonial cells can be found in which the two V's 

 and the accessory are readily distinguishable although the other 

 chromosomes may be too badly massed for further study (Figs. 

 61-64). 



In the first spermatocyte, the multiples are found attached 

 to each other end to end, thus forming an elongated ring. A 

 slight constriction appears where the ends of the V's meet 

 (Figs. 65-66). 



The cells in the earlier growth stages were small and the 

 chromatin so massed together that I gained nothing from them. 



