CHROMOSOMES OF THE REDUVIIDAE 333 



side view and shows clearly the relative positions of the XandF 

 elements. Only four of the five chromosomes show in this figure. 

 Although no anaphases are present in my material, I think we 

 may safely conclude, from what has been found in the rest of the 

 family, that the twelve chromosomes in the ring divide equally, 

 while the five members of the hexad group which lie in one plane 

 pass to one pole undivided and the one below or above passes 



• # •• • • 



*• A • * B 



•:. 



D 



: f*r*\ t .;• • 



••• • E t • F G H 



Fig. 1 Sinea rileyi Montd. A and B, metaphase plates of the first spermato- 

 cyte division showing eighteen chromosomes, six of which are noticeably smaller 

 than the remaining twelve; C, a side view of an anaphase of the first spermatocyte 

 division showing that the small chromosomes divide in this division; D and E, 

 metaphase plates of the second spermatocyte division with twelve chromosomes 

 in the ring and the five chromosomes (X element of Wilson) which lie in one plane 

 in the middle; F is the same as E except it is drawn at a different iocus to show the 

 single chromosome (F element) ; G is a slightly oblique view of the second division 

 to show the hexad group in the middle; H is a side view of the second division and 

 shows the relative positions of the A' and Y elements (only four of the five chromo- 

 somes show in this figure). X 2275. 



to the opposite pole undivided. This would give two classes of 

 spermatozoa, one with thirteen and one with seventeen chromo- 

 somes and the fertilization formula would be as follows : 



