284 . THEOPHILUS S. PAINTER 



While a number of fixing fluids were tried, the author has 

 obtained his best fixation by using cold Flemming's solution with 

 urea, after the method of Hance, and Allen's modification of 

 Bouin's fluid. The methods of hardening and dehydration as 

 described by Hance ('17) and by Allen ('19) were followed. 

 Of these two methods the modified Bouin's fluid on the whole 

 gave the better results. However, my experience has been that, 

 for somatic or spermatogonial divisions, the cold Flemming 

 method gives a better separation of the chromosomes. 



In all cases the spinal cord of the lizard was cut just behind 

 the skull. The abdomen was then opened, the testes removed, 

 split open, and immediately put into the preserving fluid, where 

 the tubules were teased apart. This insured rapid and complete 

 fixation. 



The lacertelian testis is made up of convoluted tubules, much 

 the same as have been found in all higher vertebrates. In general 

 the various cell generations may be found as follows: spermato- 

 gonia lie on the periphery of the tubule, just within this outer 

 circle one finds the first spermatocytes in their various stages, 

 and the second spermatocytes and spermatids surround the 

 lumen of the tubule. Exceptions to this arrangement are 

 numerous, especially in the testes of mature males, but one has 

 no difficulty in distinguishing cells of the various generations, 

 since the size of the cells and the shape of the chromosomes are 

 markedly different in these several stages. Supporting cells are 

 commonly seen in the walls of the tubules, but I have failed to 

 find anything which could be identified as true Sertoh cells. 



In all the lizards studied, and this is especially true of the 

 Iguanidae, the chromosome complex is made up of two sets of 

 bodies strikingly different in size. In figure 1 a dividing sperma- 

 togonial cell is shown. It will be noted that there is an outer 

 circle of large V-shaped chromosomes, while within the center 

 of the spindle is filled with a number of dot-like chromosomes. 



Hamblett, for catching many of the males upon which this study was made. 

 Through their knowledge of the habits of the commoner species, together with 

 their agility, they were able to run down and catch some forms which otherwise 

 I should not have been able to obtain. Due acknowledgment is made to these 

 gentlemen in this place. 



