144 
Femandus Pa^Tie 
sperm egg 
11 + 12 = 23 cf 
12 + 12 = 24 Ö 
^^^lethe^ or not the odd chromosome and the unequal pair of idio- 
chromosoines remain in a Condensed form diiring the growth period, 
I am unable to say as my material does not demonstrate this point. 
Accordingly, I am also unable to say, whether the components of the 
idiochromosome bivalent, pair at the synaptic period or just pre\dous 
to the first dmsion. 
General. 
Since I have given three interpretations to this peculiar chromo- 
some combination it may be well at this point to discuss them briefly. 
The first interpretation, I think, can be rejected without much considera- 
tion. The single odd chromosome cannot be a supernimierary chromo- 
some on accoimt of its regularity in beha\’ior and its definite correlation 
with sex production. In the first division it always passes imdmded to 
the same pole as the large idiochromosome or to the female producing 
pole and divides in the second. The supernnmeraries of Metapodius 
divide in the first division but pass to either pole in the second; those 
of Diabrotica divdde in either division and pass undivided to either pole 
in the other division. In both cases the supernnmeraries bear no re- 
lation to sex. 
There is a better basis for the second interpretation, especially so 
when we compare the combination in Gryllotalpa with those found in 
the Redindidae (Payne ’09) and in Thyanta (Wilson ’IO). I reahze 
there is danger in comparing the chrornosomes in two groups so videly 
separated as the Hemiptera and Orthoptera, yet it seems to me if there 
has beeil an evolution in chromosome formation and combinations, as 
there certainly has been, this evolution must have taken place along the 
same general lines in aU forms. In Conorhinus, Fitchia and Thyanta 
the large idiochromosome is represented by two or to use Wilson’s term 
the X-element is double and the two chrornosomes which form it pass 
as a unit to the same pole in the second division. This is practically 
what we find in Gryllotalpa except that the two chrornosomes (those 
which I have caUed the large idiochromosome and the odd chromosome) 
pass to the same pole in the first division instead of the second. The 
intimate association, however, between the two chrornosomes of the 
X-elenient found in Conorhinus, Fitchia and Thyanta is not present in 
