CHROMOSOME GROUP IN BRACHYSTOLA MAGNA. 



33 



the preceding telophase, but instead of exhibiting a longitudinal 

 split they arc seen to be composed of two equal limbs joined together 

 at one end only (Fig. 9) just as illicit they passed to the pole in the 

 previous anaphases. The division occurs at the point of junction 

 of the two limbs and is unquestionably transverse separating' 

 the tivo chromosomes at the point where they fused in synopsis two 

 generations before. 



In those secondary spermatocytes in which the accessory chro- 

 mosome occurs, this element also divides, but in the line of the 

 longitudinal split which has persisted from the prophases of the 

 primary generation. One half of the resulting spermatids, there- 

 fore, are characterized by the presence of the accessory and the 

 other half by its absence, but this constitutes the only mor- 

 phological difference between the two categories. In each, the 

 ordinary chromosomes may be seen to constitute a graded series 

 of eleven members in which a considerable gap at one point 

 separates a subgroup of three small units from another sub- 



FIG. 10. 



FIG. ii. 



FIG. 10. Polar view of chromosome group in metaphase of secondary spermato- 

 cyte containing the accessory chromosome. Eight large and three small ordinary 

 chromosomes appear. (From section. ) 



FlG. II. Axial view of chromosome group of ovarian follicle-cell in telophase. 

 Twenty-two chromosomes appear of which six are decidedly small and the other six- 

 teen decidedly larger. 



group of eight larger ones (Fig. 10). The series therefore repre- 

 sent exactly half of the ordinary chromosome group as we found 

 it throughout the secondary spermatogonia. This is the chro- 



