478 D. H. WENRICH 



gation begin at the apices of the V's and proceed toward the 

 ends, or does it begin at the free ends and proceed toward the 

 apices? The drawings shown are not entirely conclusive on 

 this point, though very suggestive. In figure 2 the two synaptic 

 points are marked by deeply stained knobs to which the 'ves- 

 icles' are attached. These knobs are not situated at the proxi- 

 mal side of the nucleus, but appear to have been pulled away 

 from this position which they undoubtedly held in the telophase 

 of the last spermatogonial division (figs. 7 and 8). The knobs 

 are at the apex of an angle made by a sharp bend in the threads 

 at that point, and while the knobs themselves stand somewhat 

 apart, the threads appear to be conjugated for a short distance 

 on either side of them. When I attempted to follow these con- 

 jugated threads they soon became lost in the maze of unconju- 

 gated, single threads. The appearances, however, indicate that 

 the only parts of these threads which had conjugated at the 

 time were those immediately adjacent to the appendage-bearing 

 knobs, and therefore at the apices of the V's. 



In figure 3 a situation is presented somewhat similar to that 

 in figure 2, except that here conjugation has taken place on 

 only one side of the apical knobs, the remainder of this pair of 

 threads apparently consisting of unpaired leptotene strands. 

 In figure 4, conjugation of this pair has gone further, but even 

 in this case the conjugated part is confined to the region on 

 either side of the synaptic points. These cases, together with 

 others which have not been drawn, tend to support the idea that 

 conjugation of the atelomitic chromosomes begins at the apex 

 of the V, which, as the point of spindle fiber attachment, is 

 homologous with the proximal end of the telomitic or rod-shaped 

 chromosomes. 



As soon as conjugation is complete, all of the chromosome 

 threads appear d.ouble, as shown in figure 5, which represents 

 the pachytene stage. In this nucleus, the usual orientation of 

 the chromatic elements has been lost. There is some tendency 

 for the threads to be centered toward the side of the nucleus 

 which is uppermost in the drawing, but the accessory chromo- 

 some (X), which is customarily attached at the proximal pole 



