IO4 



CYTOLOGY 



CHAP. 



The two different ways of obtaining the same end result the pro- 

 duction of the two types of spermatozoa in equal numbers may be 

 represented in a diagram as follows : 



First division equational. 

 Second division reductional. 



First division reductional. 

 Second division equational. 



Spermatocyte I. 

 Spermatocyte II. 



Spermatid. 



(3) Variotis forms of the X and Y Chromosomes 

 A frequent feature of the X chromosome is that it is compound, 



\\A\I I//7T 



-Y 



H 



FIG. 48. 



The chromosomes of Gelastocoris. (Payne, B.B., 1909.) A, ? diploid group, 30+2X4 = 38 chromosomes; 

 B, o* diploid group, 3O + X4+Y = 35 chromosomes; C, metaphase I., 6". I5 + X4+Y-2O chromosomes; D, 

 metaphase II., $ ; the sex chromosomes are in the middle of the ring, the four components of the X chromo- 

 some in a group opposed to the single Y chromosome which is partly underneath them ; E, metaphase II., ; 

 F, anaphase II., <J ; G, H, polar views of anaphase II., <$ G with the Y chromosome, H with the X group. 



