316 THEOPHILUS S. PAINTER 



early to one pole of the cell, undivided. As a result, the sperm 

 are dimorphic as regards the sex-chromosome. 



5. The spermatogonia of Sceloporus undulatus V. consobrinus 

 show twelve macro- and about eighteen micro-chromosomes. 

 An X-element is present, and behaves as it does in Anolis and 

 and S. spinosus. 



6. The spermatogenesis of Holbrookia texana is essentially 

 like that of the foregoing forms. There are twelve macro- and 

 twenty-two micro-chromosomes in the spermatogonia. An 

 X-element was found, and the sperm are dimorphic as regards 

 it. 



7. The spermatogenesis of Uta ornata was only partly worked 

 out. There are twelve macro- and about eighteen micro-chro- 

 mosomes in the spermatogonia. While the X-element was not 

 identified in the first maturation division, the second spermato- 

 cytes were found to be of two kinds, part with five and part with 

 six macro-chromosomes. Hence this species -is like the rest 

 described. 



8. The chromosome complex of Crotaphytus collaris was deter- 

 mined. There .are twelve macro- and from twenty-four to 

 twenty-six micro-chromosomes in the spermatogonia. The 

 primary spermatocytes show a halving of these numbers. 



9. A fragmentary description of the spermatogenesis of Cnemi- 

 dophorus gularis is given. This species belongs to a different 

 family from the rest which were worked upon. 



10. Sex-determination in lizards is of the 'double accessory' 

 type; that is, the X-chromosome is derived from two spermato- 

 gonial chromosomes. The males are heterozygous as regards 

 sex. 



11. A study of ovarian tissue in Sceloporus spinosus indicated 

 that the female was of the 2X condition, for two more macro- 

 chromosomes were found present than in the males. 



12. Dividing somatic cells of Sceloporus embryos show either 

 twelve or fourteen V-shaped macro-chromosomes. The number 

 is constant for the individual; that is, we find always the same 

 number in a given embryo. The embryos with twelve macro- 

 chromosomes would have become males and the ones with four- 



