362 KANSAS UNIVERSITY SCIENCE BULLETIN. 



eccentric member shows remarkable constancy in size. Its 

 size and its position suggest the accessory during synapsis. 

 See figures 29, 30, 33, plate LXV. Figure 5, plate LXVIII, 

 shows a polar view of an atypical metaphase. This condition 

 was observed only twice in this material, both times occurring 

 in different individuals. There appear to be twelve chromo- 

 somes present. In addition to the small chromosome within 

 the ring, there are two large equal elements which are not 

 large enough to correspond to any elements present in the 

 typical metaphase. Only eight chromosomes form the ring. It 

 must be that the missing one of the nine which usually form 

 the ring is represented by the two small and unusual bodies 

 which lie within the ring, one on either side of the small ele- 

 ment, and that this is merely an accidental case in which 

 synapsis did not occur. In connection with this supposition we 

 recall the fact that synapsis did not occur in the small chromo- 

 some at the usual time. This similarity of action during the 

 synaptic period may be significantly related to their similarity 

 of position. 



In a lateral view of a spermatocyte anaphase the same sur- 

 face of the chromosomal elements is presented to the observer 

 as is seen in the equatorial plate of the spermatogonial cells. 

 By referring to figures 1 to 10, plate LXV, it will be seen that 

 the chromatids have become slightly shorter and correspond- 

 ingly thicker. Here again the smallest chromosome asserts its 

 independence. In the spermatogonial cells these small chromo- 

 somes present spherical outlines. In the first spermatocyte 

 generation, instead of shortening, as their fellows, they have 

 elongated. Only in this element and in the accessory was the 

 plane of division actually determined. Since the two halves 

 of the smallest chromosome are never so closely united that we 

 lose sight of their identity, it can be stated positively that 

 division in this case is transverse and qualitative, causing the 

 separation of maternal and paternal elements. Owing prob- 

 ably to the slight attraction exhibited between the halves of 

 this chromosome division is effected while the other chromo- 

 somes are still intact. Lateral views of early anaphases in- 

 variably show this condition. Similar views of later stages 

 show its separated halves preceding the larger diads to the 

 poles. In the ordinary tetrads the formation of the crosses 

 might be interpreted to have the same significance as is at- 

 tributed to the like form in the Qrthoptera, in which McClung 



