98 JOSE F. NONIDEZ 
hemipteron Enchenopa (Kornhauser, ’14). Perhaps not much 
stress should be laid on this point since, as a whole, the behavior 
of the complexes during the growth period is not very accurately 
known. 
The facts just mentioned are in remarkable contrast with the 
conditions in Blaps and point to another interpretation of the 
X-complex in the latter case. But we cannot fail to recognize 
that in Blaps the assumption ofa linkage of the X-chromosome 
with two pairs of euchromosomes of unequal size also meets 
with important objections. The failure of the M-chromosomes, 
and, probably also, of the small chromosomes, to pair at synapsis, 
or, at least, to remain paired during the postsynaptic stages, is 
a noteworthy feature which departs from the conditions described 
in other forms. If we regard the M-chromosomes as euchromo- 
somes, we must accept the fact that they are of a peculiar kind. 
I must confess that definite proof showing that the M-chromo- 
somes do not undergo synapsis is lacking at present; indeed, the 
actual pairing of any chromosomes was never observed in my 
slides, and the assumption that parasynapsis occurs 1s merely an 
inference based on the behavior of the bivalents during the diplo- 
tene stage. We can be sure, however, that, in the event of a 
parasynaptic association of the M-chromosomes, this condition 
lasts but a short time, since their independence is well shown in 
the early pachytene nuclei. 
It is true that this peculiarity in itself does not give a strong 
ground for either accepting or rejecting the idea that we are 
dealing with a pair of euchromosomes linked with the sex chromo- 
some. But since no explanation of the nature of the X-complex 
is given or even suggested in the present paper, the statement 
has no other value than the recognition of a fact, the nature of 
which is still unknown. Further, such a condition is of some 
theoretical interest, since it proves in an unmistakable way the 
_ absence of crossing over for the two sets of hereditary factors 
located in the M-chromosomes, which, if we judge from the con- 
siderable size of the latter, must involve an extensive series of 
characters. 
