INEQUALITIES IN HOMOLOGOUS CHROMOSOMES a3 
Pisum the number of pairs of chromosomes (seven) is not large 
enough to account for the number of pairs of allelomorphic char- 
acters which behave independently of each other in breeding 
experiments, if we assume that the basis of each member of one 
allelomorphic pair must be permanently located in one mem- 
ber of a single pair of chromosomes: 
In Pisum eleven or more pairs of allelomorphs have been observed 
and the reduced number of chromosomes is only seven; which shows 
that in this case at least, several characters must reside in one chromo- 
some. The characters must then be confined to separate particles or 
corpuscles of the chromosomes, and an interchange of homologous 
particles according to chance during maturation would give the Mendel- 
ian combinations. 
I am not quite willing to believe that the basis of an allelomorph 
may slip from one chromosome to another. Yet it is very evi- 
dent, so far as I can see, that the number of chromosome pairs 
behaving independently of each other is too small to allow them 
to be the basis for the number of allelomorphic pairs of characters 
behaving likewise independently of each other. Possibly some 
of these extra pairs of allelomorphs may be accounted for by the 
deficient chromosome hypothesis which I have advanced, or 
possibly by the ‘chiasma’ theory of Morgan, though I have evi- 
dence against the latter in these unequal chromosomes and in the 
V-chaped chromosomes of Chorthippus and Jamaicana (Robert- 
Some 1). 
Additional instances of unequal chromosomes, so far as I 
have been able to find in the literature, have been reported 
by Baumgartner (Science *11), Hartman (713), and, I have 
been informed, by Voinov (’12). The last mentioned paper 
is published in a European journal to which I have been 
unable to get access. Baumgartner reported an unequal pair 
in Gryllotalpa, but he gave no drawings and no description. 
Since that time, Payne (’12) has shown that the unequal pair 
in Gryllotalpa is related to the sex chromosome, the larger member 
of the pair going with it in the reduction division. 
A short time ago Mr. F. A. Hartman called my attention to 
the fact that he had already described unequal divisions of some 
