CHROMOSOME STUDIES 215 



whereas the lO's are still broadly in contact along their hori- 

 zontal arms, which thus still retain the famihar cross-shaped 

 tetrad appearance of late metaphases, such as we find in species 

 like Syrbula, where only rod chromosomes are found. 



The second spermatocytes in Chorthippus are illustrated by 

 figures 184 to 186, in one of which (fig. 185) the sex chromosome 

 is wanting. An anaphase stage, showing the sex chromosome, is 

 given in figure 187. In each of these four cells are three large V- 

 shaped chromosomes. If each arm of a V be counted as a single 

 rod-chromosome, there are readily seen to be 1 1 or, with the sex- 

 chromosome, 12 chromosomes, which may be arranged in a graded 

 series according to size, as in the case of the 11 (or 12) rod- 

 chromosomes of Syrbula (figs. 159, 160). Believing that this 

 is the true condition of the chromosomes, I have given them 

 here corresponding numbers. It will be seen that no. 11 is 

 attached to 7, 10 to 8, 9 to 5. The points of attachment are 

 constricted and show clear spaces, as usual, where the two 

 chromosomes have become united. The size relations of V's, 

 and of all the other chromosomes, are the same as in first sperma- 

 tocytes and spermatogonia. 



3. Chorthippus bigiiUulus Linn. For sake of comparison with C. 

 curtipennis I have copied two of Gerard's ('09, p. 582) figures of 

 C. (s.) biguttullus, and have attempted to number the V-chromo- 

 somes (my figs. 188, 189) like those in curtipennis. From the 

 lengths of the limbs of the three V's shown here, one would 

 conclude that probably the same chromosomes are concerned 

 in forming the V-compounds in biguttullus, a European species, 

 as in curtipennis. 



4. Resume on Chorthippus and Syrbula. (1) The study of 

 tettigidean chromosomes has shown that the same numbers 

 and, within certain limits, the same size relations are found 

 among all the genera of a family. Syrbula and Chorthippus are 

 closely related genera of the acrididaean subfamily Truxalinae. 

 They differ apparently in the number of chromosomes. Both 

 have one (cf's) or two ( 9 's) sex chromosomes. Syrbula has 

 eleven pairs of rod-shaped autosomes; Chorthippus has three 

 pairs of V-shaped and five pairs of rod-shaped autosomes. 



