CHROMOSOME STUDIES 253 



some series of pairs. Now, apparently, after going through all 

 of these stages, these spiremes exhibit interlockings between 

 pairs of V's, such as the Schreiners and I have described; inter- 

 lockings which I believe must have been made at the beginning 

 of parasynapsis. This to my mind is of significance, and means 

 that these pairing chromosomes probably maintain their individ- 

 ual identity while passing though these stages, and that there 

 is probably not so intimate a fusion of them as to necessarily 

 result in loss of continuity as a thread. 



Further evidence that parasynapsis probably does not result 

 in complete fusion of the pairing chromosomes can be drawn 

 from the V-rod pairs of Jamaicana subguttata, providing we 

 assume parasynapsis to have taken place in this double pair 

 (figs. 197-199; also Woolsey, '15, figs. 37^6). If we make 

 this assumption, then in the process of disjunction the proximal 

 ends of the rod-mates have evidently rotated away from the 

 proximal region (apex) of their V mate until each of the rods 

 has come into line with its respective limb of the V, as is shown 

 in most of the figures (fig. 37 especially). All division figures 

 found in which this V bi-tetrad could be studied gave distinct 

 proof that the length of the no. 16 rod corresponded with the 

 length of the no. 16 limb of the V, and the length of the no. 14 

 likewise with its limb of the V. In all such divisions this long 

 bi-tetrad V with segmented limbs was the only form in which 

 the body appeared. This is evidence to my mind that these 

 rods in separating from their respective limbs of the V have 

 separated along the plane in which the side-to-side pairing took 

 place. Otherwise, if a complete fusion of these rods with the 

 limbs of the V had taken place with possibly splitting in a new 

 plane, there would have resulted a variety of forms of this com- 

 pound body ranging from the long bi-tetrad V form we have here 

 to an elongated unequal sided ring, such as is found to be con- 

 stant for the species Jamaicana unicolor (fig. 201; Woolsey, 

 '15, figs. 65-67). The constancy with which this V separates 

 from its rod-mates in unmodified form is strong though indirect 

 evidence that parasynapsis, if it occurred, was not as complete 

 a fusion as Bonnevie and Vejdovsky would maintain. 



