292 THEOPHILUS S. PAINTER 



the preparations showed that S. spinosus differs in no marked 

 respect from AnoHs. 



In equatorial plate views of the first maturation spindle there 

 are six macro-chromosomes and, typically, five micro-chromo- 

 somes. This shows that there has been a pairing of "all the 

 spermatogonial elements. Considering first the macro-chromo- 

 somes, we have little difficulty in identifying the 'a,' 'b,' and 

 ' c' chromosomes, and in addition a bipartite chromosome labeled 

 X. Generally, all the macro-chromosomes, except the X and 

 the 'b' chromosomes, show their tetrad character (figs. 28 and 

 30). The micro-chromosomes are much larger than similar 

 bodies in Anolis; in fact, in S. spinosus there is less difference 

 in size between the largest micro-chromosome and the 'b' chro- 

 mosome than between the 'b' element and any of the macro- 

 chroinosomes, excepting 'c' Frequently one of the micro- 

 chromosomes lies so that both halves of it may be seen (figs. 

 28 and 30). 



In side views of the first maturation spindle one sees in perhaps 

 a third of all the cases a bipartite chromosome (marked X) 

 passing undivided to one pole of the cell. The size and shape 

 of this X-element varies somewhat in different cells, but its 

 bipartite character is strongly marked in every case (figs. 31 to 

 33). In other respects the first division goes forward normally. 

 In figure 33 the 'b' chromosome and several of the micro-chro- 

 mosomes have divided. 



On the basis of the first division, one should expect that the 

 secondary spermatocytes would be of two kinds, half with, and 

 half without the X-chromosome. 



Second maturation division. The precocious splitting of the 

 chromosomes as they come out of the resting nuclear stage makes 

 a study of second spermatocyte divisions difficult. In favorable 

 cells, however, one may clearly make out either five or six macro- 

 chromosomes. Figure 34 shows a cell with five, and figures 35 

 and 36 show cells with six large chromosomes. The X-element 

 is marked in figure 36. 



