REPTILIAN SPERMATOGENESIS 291 



Spermatogenesis of Sceloporus spinosus 



This common Hree lizard' has proved to be a very satisfactory- 

 form upon which to work, because the germ cells are large and 

 preserve well with either cold Flemming or modified Bouin; 

 there are relatively few micro-chromosomes to be found in the 

 spindles and they are large, and the X-chromosome element 

 is seen passing undivided to one pole in the first maturation 

 division more often than in any other lizard studied. As a 

 glance at the figures of plate 3 will show, the behavior of the 

 chromosomes in Sceloporus spinosus during maturation is closely 

 similar to what is found in Anolis carolinensis. 



Spermatogjonia. Dividing spermatogonia (figs. 25 to 27) 

 show a condition strikingly similar to that of Anolis. In equa- 

 torial plate view there are twelve macro-chromosomes, forming 

 a general circle, and ten micro-chromosomes lying scattered 

 over the center of the spindle. 



A close study of the macro-chromosomes shows one pair longer 

 than the rest, labeled 'a,' a small pair, labeled 'b,' markedly 

 smaller than the other V's, and in figure 25 a third pair, 'c,' is 

 seen, somewhat larger than 'b.' (Fig. 25 is a cell preserved in 

 cold Flemming, while figs. 26 and 27 are taken from cells preserved 

 in Allen's modification of Bouin.) The six remaining chromo- 

 somes are all about the same size. A comparison of figures 

 25 and 26 with figures 1 to 3, taken from Anolis, shows that, 

 as regards macro-chromosomes, the two forms are similar in 

 number and general size relations. The 'b' chromosome pair 

 of S. spinosus is relatively much smaller than the corresponding 

 'b' chromosomes of Anolis. 



The micro-chromosomes of S. spinosus are ten in number 

 and are comparatively large in size. In addition to the rounded 

 balls one also finds somewhat elongated blunt rods, as shown in 

 the figures. 



First maturation division. No detailed study was made of 

 the various phenomena exhibited by the nuclear elements up 

 to the prophase of the first division. A casual examination of 



