AND MENDEL’S LAW 267 
somatic and reducing divisions respectively, can 
scarcely fail to be struck by the extraordinary simi- 
larity between the two processes. It seems quite 
clear that there must be some real connection between 
the behaviour of chromosomes as seen microscopically 
on the one hand, and the behaviour of allelomorphic 
characters as deduced from the results of experiment 
on the other ; and that the evidence derived from these 
two forms of study is bound to be of considerable 
mutual benefit. 
At first sight it might be thought that the chromo- 
somes are the actual bearers of Mendelian characters, 
in the sense that each chromosome represents a single 
allelomorph ; and, indeed, there is no fundamental 
difference between the behaviour of chromosomes and 
that of our supposed character-bearing particles. But 
there is, at least in some cases, a fatal objection to 
this belief in the fact that in certain plants the number 
of separate allelomorphic pairs which may be born by 
a hybrid is greater than the reduced number of chromo- 
somes which the germ-cells of this hybrid contain. 
For instance, in the case of the pea the reduced 
number of chromosomes is seven, and Mendel himself 
described the behaviour of seven independent pairs of 
allelomorphs in peas. Recent study has revealed the 
presence of at least four additional pairs of allelo- 
morphs in these plants, all of which are probably equally 
independent of one another. 
We must, therefore, seek a different explanation, 
and de Vries has recently suggested one which up to 
