64 H. B. GOODEICH 



2. Presynaptic and synaptic stages. The seriation of the 

 presynaptic stages cannot be determined from the position of 

 the cells in the testis as various conditions are often found with- 

 in a single section. From synizesis onward, however, the seria- 

 tion is perfect and using this as a point of departure it is possible, 

 from considerations of nuclear size and structure to determine 

 the preceding seriation. The resting nuclei (fig. 4), indistinguish- 

 able from the similar condition of the spermatogonia, contain 

 chromatin irregularly distributed, not infrequently showing 

 paired granules on parallel linin threads, and a large plasma- 

 some centrally located. The succeeding stage (fig. 5), most 

 clearly seen in preparations from the testis fixed in the Flem- 

 ming-urea mixture, show more conspicuously the paired chroma- 

 tin bodies lying on parallel threads which are frequently at- 

 tached to the plasmasome. These chromatin masses cannot 

 be accurately counted as it is seldom that the chromatin is so 

 sharply concentrated in these bodies as in figure 5, but here they 

 certainly do not exceed the diploid number of chromosomes. 

 At this time the process of leptotenization begins (figs. 6 and 7). 

 The chromatin becomes distributed upon the lengthening 

 threads which are often clearly parallel and bear paired granules, 

 and the process continues until the nucleus becomes so filled 

 as to defy analysis. Contraction begins during the later lepto- 

 tene and early synaptic stages (figs. 7 and 8), the threads ap- 

 pear more heavy and bear a more uniform distribution of chroma- 

 tin (fig. 8). The plasmasome moves to the edge of the mass 

 thus indicating polarization. The continuation of this process 

 culminates in a. typical condition of synizesis (fig. 9). During 

 contraction, threads, sometimes paired, loop out from the 

 central tangle into the clear surrounding nuclear spaces. Figure 

 10 shows an early stage in the release of the synaptic knot. 



3. Postsynaptic stages. Synizesis is followed by a peculiar 

 pachytene nucleus apparently characteristic of the spermato- 

 genesis of the genus (fig. 11). Heavy ribbon-like threads bear- 

 ing chromatin at either edge (sometimes granules on opposite 

 edges are conspicuously paired) rigidly traverse the nucleus 

 from the centrally located plasmasome to the nuclear wall; 



