570 CLARENCE E. McCLUNG 



At this point it may not be out of place to speak of the condi- 

 tion of cross segmentation as an index of chromosome bound- 

 aries, since this is a matter that has led many, including myself, 

 into mistakes. These non-chromatic segments are doubtless 

 definite indications of structure in the chromosome and prob- 

 ably are always of the nature of the spaces lying between the 

 chromomeres, as in the 'selected ' chromosomes described by 

 Wenrich ('16). Such regions are more pronounced in appear- 

 ance and more persistently free of chromatin where the fiber 

 attaches than elsewhere in the chromosomes, but probably do 

 not differ otherwise. Even this distinction may be lacking, as in 

 Mermiria (figs. 58, 59, pi. 7) where the chromosomes seem not 

 infrequently to separate at different levels. It was this strong 

 cross segmentation at definite levels, with subsequent division, 

 that led me to believe in the. decad constitution of the multiple 

 in Mermiria. 



Another thing which has contributed to Robertson's mis- 

 interpretation of the V-chromosome is his belief that only in 

 their presence do pachytene loops appear in the nucleus. No one 

 feature is more characteristic of the prophase condition in all 

 Acrididae (from which the Tettiginae should be removed, as I 

 suggested in 1908 and as Robertson believes) than the bending 

 of the chromosome so that both ends lie at one side of the nu- 

 cleus. Even the univalent accessory chromosome takes this po- 

 sition, as was shown in an earher paper ('02, fig. 12). Wenrich 

 finds that the looped condition is not confined to the large ele- 

 ments, but is characteristic of the small chromosomes of which 

 he made careful, detailed study. It is of interest to note that, 

 in this respect, the members of the octad in H. viridis behave as 

 though they were independent, each forming its own loop. 

 This is a very strong indication, indeed, of their multiple nature. 

 The conditions at this time in the Tettiginae are unique so far 

 as my experience goes Here, as Robertson states, the chromo- 

 somes are extended in a more or less straight line, and since they 

 are much longer than the nuclear diameter, the whole nucleus is 

 drawn out, producing very irregular shaped structures. It 



