412 MITCHEL CARROLL 
a number of instances in Camnula where the two members of a 
pair had either failed to synapse or had divided precociously; 
one instance is shown in figure 10 where pair no. 10 exhibit this 
abnormal behavior. 
Thus, there is evidence enough that unpaired supernumeraries 
may originate through the aberrant behavior at times of chromo- 
somes in the maturation divisions. 
I have found no records in the literature of observed abnor- 
malities in the division of spermatogonial or oogonial chromo- 
somes. I have observed none myself. In the metaphase seen 
in figure 133, plate 14, however, in the upper left quadrant, is a 
chromosome with a very marked constriction. In the same 
individual from which this drawing was made, another spermato- 
gonial complex was found with two chromosomes having similar 
constrictions. It is conceivable that in anaphase a break might - 
occur in one chromatid at the point of constriction, and one and 
one-half chromatids might pass to one pole, while the deficient 
chromatid passed to the other. There might thus arise an un- 
paired supernumerary and an unequal pair. Although no irregu- 
larities in the division of spermatogonial chromosomes that might 
give rise to a supernumerary, the duplicate of an entire member 
of the normal complex, have been reported, it 18 entirely reason- 
able to suppose that abnormal divisions sometimes occur. Extra 
elements may thus arise in the spermatogonia, as in the first 
spermatocytes, as the result of breakage or of premature or de- 
layed divisions, followed by non-disjunction of the members of a 
chromosome pair. . 
Wilson identified (07 b, ’09 b) the from one to five supernum- 
eraries occurring in certain individuals in Metapodius as extra 
idiochromosomes on. account of similarities of size and form, be- 
havior in the growth stages, and the fact that they typically con- 
jugated with the idiochromosomes to form multiples of higher 
valence than tetrads. In one individual of Metapodius femora- 
tus Wilson (’10) found that the unpaired supernumerary exhib- 
ited no precocity in the growth stage and united with the m-chro- 
6 These constrictions in camnulan chromosomes do not appear to be constant 
for the race, or the individual, as in Decticus (Mohr, 719). 
