3OO L. J. BACHHUBER. 



fine threads constituting the leptotene threads, leaving two, still 

 rounded chromosomes, which can from this time on be identified 

 as the accessories. The leptotene threads, in both sections and 

 smears, are seen to persist as independent units. Their exact 

 number could not be determined because of their extreme length. 



During this stage, the accessory elements remain as small 

 spherical masses which can easily be identified if the mass of 

 leptotene threads is sufficiently destained. During the process 

 of synapsis also, the X and the Y remain unchanged, always close 

 together, and sometimes apparently connected by thin, dark- 

 staining threads of chromatin material (Fig. 15). No instances 

 have been found which at this stage show the accessory elements 

 in different portions of the cell. 



In these prophases, the presence of the chromatoid body 

 becomes definitely established. It stains similarly to the chro- 

 matic material in the iron-haematoxylin, the Delafield's haema- 

 toxylin, and in the Flemming's triple stain. Just where this 

 body arises is still a question. As before stated, it has been 

 found in only one spermatogonial cell and that was a rather 

 doubtful case. In the primary spermatocytes it is absolutely 

 constant (Figs. 16, 20, 22). In a few rare cases, two and some- 

 times three have been found, but these extra bodies w T ere always 

 very small and disappeared in later stages. The large body 

 can be traced through the remainder of the process of spermato- 

 genesis. Further mention of its behavior will be made later. 



In the synezesis stage (Figs. 13-16), the threads drift and mass 

 at one pole of the cell into a grouping which has apparently no 

 established order and from which nothing definite could be deter- 

 mined. Occasionally the threads seem to have a parallel 

 arrangement suggesting parasynapsis, but when they come out 

 of the synezesis stage, considerable evidence points to a chiasma- 

 type synapsis (Figs. 18, 19). The threads are wound around 

 each other, making possible a division later in which each of the 

 haploid chromosomes would be made up of alternating segments 

 of chromatin material, from the respective leptotene threads 

 of the conjugating pair. That the threads still retain a con- 

 stancy in number seems highly probable for in favorably stained 

 sections where their ends can be seen, the number never exceeds 



