182 WM. EEES B. ROBERTSON 



tera examined for chromosome conditions increases from year 

 to year, the results tend to confirm the correctness of this view. 

 In the chromosomes of Orthoptera we seem to be deahng with 

 morphological structures possessing a definite relative size and 

 constitution as permanent as the cell itself. Their size rela- 

 tions and their behavior are probably constant, not only for all 

 cells of an individual, but for every individual of the species. 

 These size relations may vary, it is true, to a slight extent in 

 the different species of a genus, as would be expected, and still 

 more when the species of different genera are compared ; but they 

 may be reasonably constant within these limits for the sub- 

 family, and, in many cases, for the family. Thus the degree of 

 relationship is expressed as accurately in the nucleus as in any 

 of the external body characters. A distinguishing feature in 

 a germ-cell is, however, of much more importance than any 

 character of the rest of the body, since it is located in a structure 

 which may be considered the starting point of a new organism, 

 and accordingly has an important role during the development 

 of the body in the formation of all distinguishing characteristics 

 of the individual — thus influencing not one part or organ, but 

 many. 



McClung held that for the Acrididae there are twenty-three 

 chromosomes (2iV — 1)^ in the male and for the Locustidae and 

 Gryllidae each thirty-three. He did not make the count in 

 the female, which has since been found to be 2A^; i.e., one more 

 than in the male. So far as the Acrididae are concerned, these 

 numbers will have to be modified to this extent. The subfamily 

 Pamphaginae has 19 (cf) and 20 ( 9 ) (Granata, '10). This is a 

 decided exception. Possibly a multiple chromosome may be 

 involved, as in some Truxalinae and Acridiinae. Barring the 

 Pamphaginae, McClung was correct, for the Tettigidae (figs. 

 1-6, 9-13), which have 13 ( cf ) and 14 ( 9 ) as the 2A - 1 and 2A 

 numbers respectively, are possibly not related to the Acrididae 

 as a subfamily (Tettiginae) and so might be expected to have 

 peculiar chromosome conditions. 



^ The designation A'' is used to indicate single or haploid number of chromo- 

 somes, 2N thus being the formula for the diploid or somatic number. 



