518 



stage a number of long chromatin bodies, each of which is split longi- 

 tudinally (Fig. 11). At the middle point of these segments the split 

 is wider than elsewhere, and this marks the region of an ensuing 

 transverse division which corresponds to the separation of the ends 

 of the Vs in Anasa. The segments are never bent sharply at this 

 point at they are in Anasa, though, as will be described later, they 

 may be greatly curved. These segments now condense, and all traces 

 of the longitudinal split are either entirely lost or are only recognizable 

 as faint constrictions at the ends (Fig. 12). The transverse con- 

 striction is much more prominent, and the chromosomes resemble 

 those shown in Montgomery's Figs. 4 and 5. 



Before going into the division of these tetrads we must describe 

 the rings which are frequently found in these forms and which are 

 of considerable interest and importance as they are unlike any pre- 

 viously described. These rings are formed in the following manner; 

 a long longitudinally split segment such as Fig. 11 becomes curved 

 so that its opposite ends approach each other (Fig. 13), and finally 

 fuse to form a ring-like body (Fig. 14). As the segment from which 

 this body was formed was split longitudinally and consisted of two 

 halves parallel to each other, this body really consists of two rings, 

 parallel to each other. The body now has somewhat the appearance 

 of a finger ring from which the stone has been removed; the wider 

 portion, which is opposite the point of fusion of the ends of the 

 segment, represents the wider middle region of the long segment 

 (Fig. 11), and thus corresponds to a transverse division. The chro- 

 matin contracts, the rings becoming smaller (Fig. 15), and finally the 

 parallel rings fuse together to form a single one, which shows its 

 double origin only by a faint constriction. Then the rings break 

 across again at the point of fusion (Figs. 16 and 17), and this 



Fig. 13 



fission apparently extends across to the opposite side, the point of 

 the original transverse division, thus forming a body, which, when 

 seen from the side api)arently consists of two parts (Fig. 18). Each 

 of these half rings is really composed, as we know from the above. 



