300 THEOPHILUS S. PAINTER 



In such cases I found typically fourteen macro-chromosomes, 

 though the counts varied between thirteen and fifteen. In 

 only two or three cases did I find dividing cells in which I was 

 confident that there was no error in my count, and these gave 

 fourteen macro-chromosomes as the female complex. 



The evidence for the conclusion that in females of both 

 Anolis and Sceloporus there were fourteen macro-chromosomes 

 was so meager that a study of the dividing somatic cells of 

 embryos was undertaken in order to get further light upon this 

 point. 



At the outset the author was aware that chromosome counts 

 made on dividing somatic cells may not be accepted unhesitat- 

 ingly as proof of the number of chromosomes which will be found 

 in the germ cells of the individual. A number of investigators 

 have shown both for vertebrates and invertebrates" that the 

 number of somatic chromosomes may vary from that which one 

 would expect from a study of the germ cells. More recent work 

 has indicated, however, that this variation in chromosome num- 

 ber is either due to a fragmentation of one of more of the chro- 

 mosomes (Hance, '17) or that we have multiples of the haploid 

 number (Holt, '17) due to a longitudinal splitting of the chromo- 

 somes. Hance's work is of especial interest, in connection with 

 lizard embryos, since from his study of dividing somatic cells 

 of the pig he was able to show that variations from the diploid 

 number (forty) were due to the fragmentation or breaking of 

 some of the normal chromosomes, and not due to the addition 

 of new chromatin elements. 



In Sceloporus spinosus, the form upon which the following 

 work was carried out, the large macro-chromosomes have fairly 

 characteristic shapes (V's of various sorts) and there are 

 relatively few of them. On the basis of the study of sperma- 

 togenesis, it was clear that the X-element found in the first 

 maturation division was derived from two medium-sized sper- 

 matogonial macro-chromosomes. It was believed that two 

 extra V's could be detected, if they were present in the females. 



^ An excellent review of the literature dealing with this point is given by 

 Hoy ('16). 



