142 
Fernandus Payne 
are twenty-three chromosomes in the sperniatogonial groups (Fig. 1 C, 
D, E and F) and the nuinber is constant in the ten different individuals 
which I examined. Of these twenty-three chromosomes, one is noticeably 
smaller than the others and as we shall see, it is the one which I shall 
call the small idiochromosome. 
In the first spermatocyte division there are twelve chromosomes 
(Fig. 1 G,H,1 and J), one of which is irregulär in shape, offen constricted 
longitudinally and usually does not lie in the same plane as the other 
eleven. Side views of the meta- ! 
phase plate of this dmsion 
(Fig. 2 Ä, B, C, D, E and F) 
show that ten of these twelve 
are constricted dumb-bell shaped 
chromosomes. The other two, 
however, are different. One of ; 
these, which I shall designate as 
the odd chromosome and the one 
which offen appears constricted ; 
longitudinally in pole views of ' 
this division, passes undmded ' 
to one pole. It moves in ad- 
vance of the others and offen 
reaches the pole before the other 
chromosomes divide (Fig. 2 D, 
E and F). The second one is 
an elongated chromosome con- 
stricted into two unequal parts 
(Fig. 2 A, B, C, D and E), the 
large part being irregulär in shape. This unequal bivalent dmdes as a 
rule before the other ten chromosomes, the larger part moving to one 
pole and the smaU one to the opposite pole (Fig. 2 F and G). This 
unequal pah I shaU speak of as a pair of idiochromosomes in the sense 
that it was originally used by Wilson ('05). Here, however, they pair 
in the first division and divide separately in the second as in Tenebrio 
and the Diptera (Stevens ’05 and ’08). The interesting point is that 
the large idiochromosome and the odd chromosome always go to the 
same pole. That this is a constant phenomenon, I feel certain, as 
hundreds of side views have been observed and in no case have I seen 
an exception. The ten dumb-bell shaped chromosomes divide equally. 
Thus two kinds of secondary spermatocytes are produced, one contain- 
Vig. 1. 
Gryllotalpa borealis Burm. A and B, metaphase plates, 
oogonial division, 24 chromosomes; C, 1), E and F, 
metaphase plates, spermatogonial division, 23 chro- 
mosomes; 0, H, 1 and .7, metaphase plates, first ma- 
tnration division, 12 chromosomes (7, large idiochro- 
mosome and 0 , odd chromosome); K and 7., anaphase 
figures of first division from the same cell (t, small 
idiochromosome). 
