382 MITCHEL CARROLL 
THE NORMAL CHROMOSOME COMPLEX 
Excluding the Tettigidae, which apparently do not belong with 
this group, the observations of over twenty different investiga- 
tors on more than forty genera and sixty species of the Acrididae 
have shown that the diploid number of chromosomes in the 
males of this family is almost uniformly twenty-three and the 
haploid number twelve (McClung, ’14, ’17; Harvey, 716). 
Apparent reductions in number in Hesperotettix, Mermiria, 
and Chortophaga have been demonstrated by MeClung (’05, 
14, 717) to be due to the formation of multiples. Robertson 
(16) has shown that the same phenomenon is in all probability 
responsible for the apparent reduction in Chorthippus (Steno- 
bothrus). Doctor Carothers has some unpublished data of a 
similar character for Circotettix. Careful study may bring the 
other two seemingly aberrant forms, Chloealtis (McClung, 714, 
17) and Pamphagus (Granata, 710), into line with the numerical 
characteristics of the acrididaean chromosome complex. 
Some individuals of certain species, Trimerotropis fallax and 
Circotettix lobatus (Carothers, ’17), Trimerotropis suffusa (fal- 
lax?) (Wenrich, ’17), Herperotettix viridis (McClung, ’17), have 
one or two elements in addition to the typical diploid and haploid 
number. These additional elements are the supernumeraries. 
They differ from the other chromosomes in that they are not 
essential constituents of the complex. The other elements, either 
singly or as parts of multiples, are always present in every germ 
cell up to and including the first spermatocytes of every indi- 
vidual of the species, genus, and family (with the doubtful excep- 
tions noted above); the supernumeraries may or may not be 
present in the cells of different individuals of a species. 
McClung (714) reported the diploid number in the males of 
Camnula pellucida to be twenty-three, and the haploid number 
twelve. In view of the fact, as has just been pointed out, that 
these are the numbers which are found practically throughout 
the family and that counts by the writer in some thirty-four 
individuals from various sections of the United States and Canada 
indicate that in the spermatogonia twenty-three elements and 
