26 



W. S. SUTTON. 



size. In other words, there are, in the ordinary chromosome 

 group, not twenty-two but eleven sizes of chromosomes. The 

 lettering in the figure will indicate the pairs in the smaller group 

 where they are most clearly defined. 



Eight l generations of spermatogonia follow this one, and in 

 each succeeding metaphase the same number and size-relations 

 of chromosomes may be observed. This is shown in Figs. 2 and 

 3, representing different secondary spermatogonial generations, 



FIG. 2. 



FIG 3. 



FIG. 2. Polar view of equatorial plate in secondary spermatogonium of one of the 

 earlier generations. (From section.) 



Fir,. 3. Oblique lateral view of equatorial plate of a secondary spermatogonium of 

 one of the later generations. (From a smear-preparation.) Small chromosomes and 

 accessory designated as in Fig. I. 



in each of which appears six small chromosomes and seventeen 

 larger ones. In each of these also especially in the case of 

 the smaller group, the members of which, on account of their 

 nearly spherical form, do not suffer the same degree of fore- 

 shortening in the drawing as do many of their longer comrades 

 the paired relation may again be made out. Moreover, in the 

 smaller group with its fewer members and greater size-differences, 

 it is possible to see that the volume of the smallest pair (kK), for 

 instance, in one cell bears approximately the same ratio to the 

 homologous pair in another cell as does that of the largest (^/) of the 



1 Based on estimates of the number of cells in a spermatocyst at the time of trans- 

 formation to spermatocytes. 



