SYNAPSIS AND CHROMOSOME ORGANIZATION 477 



are so long and so extensively curved and coiled that they ap- 

 pear at first glance to be hopelessly tangled and to constitute a 

 network. It was possible, however, by careful study, to follow 

 some of the threads for considerable distances, but others only 

 short distances. On this account these drawings are, in part, 

 diagrammatic. 



In these lepto-zygotene nuclei there is always a tendency 

 toward an orientation of the threads just as was found at the 

 corresponding stage in Phrynotettix ('16, figs. 29, 30, 31, plate 

 3). This orientation appears to be confined mostly to the region 

 near that end of the thread to which the spindle-fiber is at- 

 tached (proximal end) and therefore that side of the nucleus 

 toward which these ends are directed is called the proximal side. 

 From this proximal side the threads run more or less parallel 

 toward the opposite side of the nucleus, thence turning to trav- 

 erse the nuclear space in various curved or convoluted courses. 

 The amount of curving depends, apparently, on the length of the 

 threads, though even the shorter ones have a tendency to form 

 a loop as is indicated by the short, deeply staining thread (5), 

 attached to the accessory chromosome in figures 1 and 4. In 

 general, only the proximal ends of the threads exhibit orientation 

 and this orientation, I believe, facilitates th-e initiation of the 

 pairing process and causes its inauguration to occur at the 

 proximal ends, as shown in figures 1 to 3. In the distal part of 

 these figures most of the -threads are single. The accessory (X), 

 usually has one end attached at the proximal pole, as shown in 

 figures 2 and 3. In figure 4 the position of the nucleus was such 

 that the orientation could not well be shown without interfering 

 with other features which it was desired to represent. 



The nuclei in figures 2, 3, and 4 were chosen for drawing be- 

 cause they show, in addition to the partially conjugated threads 

 already mentioned, certain others to which small plasmosome- 

 like bodies, or chromomere-vesicles, were appended. These 

 structures, (c), as will be pointed out later, mark the synaptic 

 points on one of the pairs of V-shaped chromosomes. 



The question has naturally arisen as to the behavior of these 

 V-shaped chromosomes in synapsis. Does the process of conju- 



JOURNAL OF MORPHOLOGV, VOL. 29, NO. 2 



