REPTILIAN SPERMATOGENESIS 287 



bodies are connected up, more or less, by strands of lightly 

 staining material (fig. 3), which increases the difficulty of counting. 



The spermatogonial division is completed in the usual way, 

 both the macro- and*hiicro-chromosomes dividing. There is 

 no lagging behind of any elements, so far as I have observed. 



First maturation division. No especial effort has been made 

 to follow in detail the changes which the chromosomes undergo 

 from the telophase of the spermatogonial division up to the pro- 

 phase of the first maturation division, although the material is 

 such that this probably could be done with comparative ease. 

 Only a general outline of the sequence of stages is given here. 



Following the last spermatogonial division, the young 

 spermatocyte enters the diffuse stage (fig. 4), at which time the 

 nucleus is characterized by the presence of two large deeply 

 staining nucleoli and scattered chromatin knots lying on the 

 linin net-work. No plasmosomes have been found at this time. 

 Apparently the formation of the leptotene threads comes about, 

 first, by an increase in the size of the chromatin knots and a 

 decrease in the size of the nucleoli, and following this, the chroma- 

 tin knots expand into the filament-like leptotene threads. The 

 nucleoli still persist as deeply staining points in the general mass 

 of chromatin threads, although they are small. No attempt was 

 made to follow the course of events during synapsis, but it has 

 been noted that no contraction stages occur in Anolis or any of 

 the other lizards studied, nor is there any marked polarization of 

 the nucleus following. The diplotene nucleus (fig. 5) is charac- 

 terized by the thick spireme threads and the presence of two 

 deeply staining elements (marked X), which appear to be more 

 or less elongated. As the diplotene threads contract to form the 

 tetrads of the first maturation division, these deeply staining 

 elements form a conspicuous bipartite body, which has a com- 

 pact form and smooth outline, while the rest of the chromatin 

 elements are still rnuch elongated. Figure 6 shows the condition 

 of such a cell. 



During this period just described, no trace of the small micro- 

 chromosomes has been found. They apparently form spireme 

 threads like the macro-chromosomes, and, indeed, in some cells 



