REPTILIAN SPERMATOGENESIS 283 



to determine what light, if any, a study of reptihan sperma- 

 togenesis would throw on the peculiar conditions found in the 

 spermatogenesis of birds, as reported by Guyer in various 

 works, since the reptiles and birds are closely related phylo- 

 genetically. 



As the following study will show, certain species of lizards 

 have been found in which the peculiar form of the chromosomes, 

 as well as their small numbers, has allowed an accurate study 

 of the spermatogenesis to be made; in fact, it has been found 

 possible to follow most of the chromosomes from the last sperma- 

 togonial division through maturation into the immature sperma- 

 tids. It must be confessed, however, that no facts have been 

 discovered which throw any light on the unusual conditions 

 reported for birds by Guyer ('16). The fact is, that during 

 maturation the chromosomes of lizards behave in quite an 

 orthodox manner, and differ in no essential respect from the 

 behavior of the chromosomes of such a classic insect as Lygaeus 

 during the corresponding period. 



MATERIALS AND METHODS 



Lizards embracing two separate families (Iguanidae and 

 Teiidae) were studied. In the case of the Iguanidae, six species 

 including five different genera are reported on. The family 

 Teiidae is represented by only one species, in the vicinity of 

 Austin, Cnemidophorus gularis. 



In one respect the lizards offer very favorable vertebrate 

 material for cytological studies. They have a very definite 

 and short breeding season and in the males of many species the 

 approach of this period is heralded by the appearance of the 

 bright colors (blues and greens usually) which mark this sex 

 during the mating season. This fact makes it easy to obtain 

 and preserve the testes when division stages are most numerous.^ 



^ Within a radius of ten miles of Austin, one finds forms characteristic of the 

 high-plateau areas as well as those forms which frequent the valleys and moist 

 areas. Capturing members of some of the species alive is no easy task, as they 

 run with what appears to be lightning-like speed. The author is indebted to 

 two students of the Zoological Department, Mr. Kenneth Cuyler and Mr. Deluz 



