280 
Sidney 1. Kornhauser 
A more detailed study of the composition and behavior of the hetero- 
clu'omosomes in spermatogenesis shows: 1. that the a;-chromosorae is 
often complex; 2. that the a>chromosome is often found associated with 
metabolic products in the growth of the sperniatocytes; 3. that 'when 
a pair of idiochromosomes is present, the x- and ?/-chromosonies show 
their affinity for each other in varying degrees in the different species 
examined; 4. that the relative size of the paired heterochromosoines 
varies greatly, and that this pair niay be connected with the autosomes; 
5. that the unpaired a:-chroniosome, or heterotropic chromosome, either 
may be coupled with a pair of autosomes in the maturation divisions 
and only occasionally separate from them, or may be partially or entirely 
independent of the autosomes, lying outside the spindle in division and 
tending to form a nucleus of its ovm. These five propositions will now 
be discussed. 
1. Gases where the x-chroniosome is represented by several chroniatic 
bodies which are still intimately associated with one another have been 
reported from diverse groups of animals. In Syromastes (Wilson ’09a, 
’09b) the a;-element is in the form of two chromosomes in the male, and 
these two a:-elenients are represented in the female by four chromosomes. 
Guyer (’IO) has reported a similar condition in the spermatogenesis of 
man. This'case, however, would seeni to need confirmation, for both 
Gutherz (’12) and Montgomery(’12) have, in the main, been unable to 
Support Guyer’s contention. An interesting possible transition stage 
from a single to a double a’-chromosome may be that of Cicindela (Ste- 
vens ’09a), where the a>-chromosome is markedly bilobed. Payne (’09) 
has shown that in Fitcliia the a-element is represented by three chromo- 
somes, in Prionidus by four and in Gelastocoris by five; in all these cases 
the a-complex has as its synaptic mate a single i/-chromosome. In 
Ascaris lunibricoides (Edwards ’IO) the a-element is composed of five 
chromosomes with no synaptic mate, the diploid numbers of chromosomes 
being 43 in the male and 48 in the female. One of the most interesting 
cases is that of Thyanta custator (Wilson ’lla), IMiereas the typical 
form has an unequal pair of idiochromosomes, the a-chromosomes being 
considerably larger than the ?/-chromosome, another race of the same 
species was found in which the a>element, though no larger than that 
of the usual type, was represented by two chromosomes. Wilson, foUow- 
ing Stevens (’06), suggests that the a’-chromosome is complex and that 
the paired idiochromosomes may be formulated as xy+y, wherein xy 
is the larger idiochromosome, and y the smaller idiochromosome. This 
interpretation would then lend an explanation to the origin of the un- 
