CHROMOSOME STUDIES 247 



In Chorthippus my conclusion is based in particular upon 

 a comparison of its total chromosome complex, V's and rods, 

 with (1) the total rod series of its nearly related genus, (2) the 

 series of its subfamily, and (3) the series of two related sub- 

 families. This comparison enables me to locate certain points 

 upon the members of three pairs of diromosomes in Chorthip- 

 pus, and by that means to identify them in the bivalent chromo- 

 somes of the first spermatocyte, at least from the stage which 

 Wilson has termed '/i' up to and through the two maturation 

 divisions to the spermatids. 



I find that all the genera of the subfamily to which Chorthip- 

 pus belongs, with the exception of a single species, the identity 

 of which is not certain (McClung, '14), have eleven pairs of 

 autosomes. These autosomes, so far as length is concerned 

 may be arranged in three groups: (1) a series of three very short 

 pairs, (2) five intermediate pairs forming a graded series among 

 themselves, and (3) three very long pairs (Robertson, '08, pis. 

 21, 22; present paper, figs. 148, 157 to 162, 178 to 180, 184 to 192). 

 I find the same number of chromosomes, and to a certain extent, 

 the same size relations in the Oedipodinae and Acridinae. If, 

 therefore, for these three subfamilies of the Acrididae there is 

 such a constant number of chromosomes and also, to a cer- 

 tain extent, of sizes, then it is reasonable to regard each of the 

 eleven pairs of autosomes as a pair of similar individual organs 

 in the cells of every species belonging to the genera of these 

 subfamilies. That established, it is possible to trace these rec- 

 ognizable pairs of autosomes through different genera, whether 

 they be separate, as in Syrbula and most genera, or linked to- 

 gether, as in Chorthippus. Syrbula and Chorthippus are two 

 closely related genera — one has no linkage in its chromosomes, 

 the other has three pairs of V's. As I have explained at pages 

 235-237, the only conclusion to be drawn, in the case of the V- 

 chromosomes at least, was that during the synapsis period they 

 had paired two by two. 



A second line of evidence that synapsis takes place is afforded 

 by the behavior of the V's in Jamaicana, where one individual 

 showed in its first spermatocyte cells a single unequal-armed 



