SEGREGATION OF HOMOLOGOUS CHROMOSOMES 487 



Mr. J. A. G. Rehn of the Academy of Natural Science for identi- 

 fication. My study of the germ cells was completed, the plates 

 made and the curves plotted before I knew the result of Mr. 

 Rehn's study. Similarly, Mr. Rehn classified the animals 

 without knowledge of my results, or even of the localities from 

 which the various specimens were taken. It is but fair to say 

 that, owing to lack of time, all that Mr. Rehn attempted to do 

 was to place the animals in the classification already established, 

 although he hopes soon to undertake a revision of the group. 



One of the most striking differences shown by the study of 

 the germ cells is the apparent reduction in number of chromo- 

 somes in the form which is unquestionably Circotettix. There 

 is no conflict here between taxonomic and cytological evidence. 

 Two species come in this division, lobatus and rabula. Un- 

 fortunately, I have only a single member of the latter species 

 and the present work has shown that any attempt to establish 

 specific differences on one or two individuals is futile for this 

 group. 



The remaining eighty-three members of this group may be 

 placed in two subdivisions, according to the number of atelo- 

 mitic chromosomes in the duplex series as is shown in text figure 1 

 (page 463). The mode for one of these subdivisions is twelve, 

 for the other seven. There is an overlapping of the two groups 

 involving twenty individuals, ten from each form. But since 

 the extremes of neither form reach to the mean of the other 

 they might constitute two distinct species. However, since 

 these groups are from widely separated localities, the differences 

 may well be due to isolation. If we consider what the expected 

 progeny of parents like number 60, form B, with its five J- 

 shaped tetrads would be, it is evident that some of the offspring 

 would be placed in form A according to this scheme. 



It is interesting to note that all members of my form A were 

 classified by Mr. Rehn as the Trimerotropis fallax of recent 

 literature. On the other hand he placed three of the fifty-one 

 members of my form B in this same species. The remaining 

 forty-eight were identified as Circotettix suffusus as that species 

 is at present recognized. He states in a note that this is a 

 "Divergent Circotettix tending strongly towards Trimerotropis." 



