CHROMOSOME STUDIES 211 



size as in Syrbula, with which the size relations are almost 

 identical. For in Chorthippus there are two large ll's (desig- 

 nated as 12's in Robertson, '08), each linked with a no. 7; two 

 lO's (ll's in '08), each linked with a no. 8; and a sex chromosome, 

 lOo;, as in Syrbula. Further, the two large 9's are linked each 

 with a no. 5. The 6's, 4's, 3's, 2's, and I's are separate, as 

 in Syrbula. The gap in size between 8 and 9 is possibly larger, 

 between 3 and 4 not so great, and between the I's and 2's a little 

 greater than in Syrbula; between 2 and 3 it is wide, as in Syrbula 

 (figs. 184-187). In general, then, the size relations of chromo- 

 somes in Chorthippus are very similar to those in Syrbula. 



As in Syrbula (fig. 149), conjugating chromosomes come out 

 of the diffuse stage in parasynapsis (figs. 163, 164). In each of 

 these cells all conjugated chromosomes (eight) and the sex chro- 

 mosome are accounted for and drawn. In figure 163 nos. 2 and 

 4 have been drawn as though moved out radially from their 

 positions; the real position of 10a; is indicated by a plus sign ( + ). 

 In figure 164 chromosomes 1, 2, 4, and lOx have likewise been 

 transferred outward. I wish to call attention to the three long 

 chromosomes (7-11, 8-10, 5-9) in these two cells. All of the 

 chromosomes show a longitudinal spht, and in parts, or all, of 

 each, a second such split at right angles to the first is evident 

 (figs. 163, 164). In figure 163 an accidental (?) interlocking 

 of the two largest chromosomes (7-11, 8-10) seems to have taken 

 place. Both show the primary split farther advanced than the 

 secondary. In 7-11 the halves gap apart in the middle re- 

 gion (x'", x"") and include between them one of the halves 

 (x') of 8-10, which is gaping apart similarly in its middle re- 

 gion (x', x"). The two chromosomes are interlocked like the 

 links of a chain. This phenomenon may be of importance in 

 the question of the continuity of the chromatin thread during 

 parasynapsis. 



The no. 4 chromosome in Chorthippus, as in Syrbula, is much 

 condensed and deeply stained. Frequently this chromosome, 

 or the end of one exconjugating hmb of it (x in fig. 168), hes near 

 one end of the sex chromosome (figs. 164, 165, 168, 170, 173, 

 174, 178b, 179, 180). In this respect it behaves similar to Mc- 



JOURNAL OF MORPHOLOGY, VOL. 27, NO. 2 



