714 C. E. McCLUNG • 



that the rings really lie in the plane of the equatorial plate and 

 not parallel to the spindle axis. 



b. Fiber attachment. This is always nearest the axis of the 

 spindle, therefore if it be at the free ends of synaptic mates the 

 point of union must be directed away from the spindle. This 

 means either that the fiber attachment has shifted to the opposite 

 end from that in the spermatogonium, or that synapsis has been 

 at the distal ends. The evidence seems to point strongly to fixity 

 of fiber attachment, and if whole spermatogonial chromosomes 

 were separated in the first spermatocyte, synapsis would have 

 to occur, or at least persist, longest at the distal ends. Either 

 assumption calls for differences between the rings and the other 

 forms of tetrads instead of conformity with them. 



c. Position of synaptic ends. If fiber attachment is at the free 

 ends of synaptic pairs then of necessity the fused ends must be 

 directed away from the spindle. This is just the opposite of the 

 conditions which certainly prevail in the case of Mecostethus 

 and all other forms with V-shaped tetrads. Not only the pro- 

 phase structure of the rings but all other considerations of order 

 in the behavior of the chromosomes speak against this view. It 

 should be noted that neither Davis nor Buchner, who figure the 

 rings with divergent cross-shaped synaptic ends in the prophase, 

 show this condition at the outer extremity of the rings in the meta- 

 phase. Here again is diversity conceived in place of uniformity. 



d. Relation of division plane to equatorial plate. In the division 

 of chromosomes, planes of cleavage lie within that of the equato- 

 rial plate, at least at the inner end where are attached the archo- 

 plasmic fibers. By the interpretation of de Sinety and his fol- 

 lowers this is not true, for the chromosomes are pulled past 

 each other in the plane of the spindle axis. This is not, in fact, a 

 division of the chromosomes in the proper sense of the term, 

 but is a mere disjunction, but one step removed from the exploded 

 'primary type' of Goldschmidt. It is to be noted here that in 

 the case of Stenobothrus, where a segregation division occurs, 

 the rings show extensive movements of the chromatids during 

 the metaphase. Divergence from normal behavior is again 

 involved in this explanation. 



