306 THEOPHILUS S. PAINTER 



number of chromosomes going to the spermatids; e) the diploid 

 number of chromosomes for the female. Points b, c, and d 

 must be known and points a and e are very desirable checks. 

 For lizards it was possible to determine all five points for one 

 species (Sceloporus spinosus) and the first four points for two 

 others (Anolis and Holbrookia). In the remaining species of 

 the family enough points were determined to be sure that they 

 conformed to the family type. The results have been consistent 

 throughout. 



In all the lizards studied two conspicuous nucleoli were found 

 in the early gj-owth period of the first spermatocytes. These 

 persisted through the various spireme stages as deeply staining 

 bodies and entered the prophase of the division as a bipartite 

 chromosome. Side views of the first division spindle frequently 

 showed this bipartite body lying outside of the equatorial plate 

 and well up or quite up to one pole. Careful study of the six 

 large chromosomes of the spindle showed that it was the same body 

 in every case which showed this movement (except for the rare 

 displacement of an autosome) and that it was not half of some 

 tetrad which had divided early. On the other hand, it must 

 be emphasized that this early migration of the bipartite chromo- 

 some is not seen in all spindles, and in some species it was not 

 seen at all. This fact led to a very careful study of late anaphase 

 stages of the first division, in order to find out if the X-chromo- 

 some really passed undivided to one pole. In every case where 

 chromosome counts could be made, one pole contained one more 

 macro-chromosome than the other, the extra element being a 

 bipartite body similar in size and shape to the X-chromosome 

 (figs. 15, 16, 17, 42, 43, and text fig. 1, C andE). Thisshowed 

 that the phenomena was a constant one, that one pole of the 

 first maturation spindle received one more large chromosome 

 than the other. 



A study of the number of chromosomes in the second spermato- 

 cytes would seem to offer a simple way of verifying first spermato- 

 cyte conclusions, but, unfortunately, this did not prove to be the 

 case with the lizards studied. When the chromosomes enter the 

 second maturation spindle, they are already, in most cases, 



