466 GAGER: CRYPTOMERIC INHERITANCE IN ONAGRA 
that we have too much neglected the extra-nuclear cytoplasm 
in the consideration of the problems of heredity. 
Whatever the mechanism of the change is conceived to be, 
the presumption is in favor of the radium rays as the determining 
antecedent condition, since such behavior, in the absence of this 
influence, has never been recorded. But that such a result as the 
double plant occurred at all is the significant botanical fact; the 
external “cause” of it is not so important.* Any explanation 
necessitates the formulation of some definite conception of the 
structure of protoplasm, and the mechanism of inheritance, and 
involves the consideration of several working hypotheses already 
elaborated. 
Perhaps the most formal of these hypotheses is that of intra- 
cellular pangenesis. The essence of this now familiar hypothesis 
is that all living protoplasm consists entirely of pangens. Pangens 
are not chemical molecules, but masses of a higher order, having 
the power of nutrition and growth, of multiplication by division, 
and of becoming active or latent according to circumstances. 
When latent they are usually in the nucleus, and become active 
only when they pass out of the nucleus into the cytoplasm of the 
cell. These pangens are the bearers of the inheritable unit char- 
acters. A change in only the number of pangens causes fluctuat- 
ing variations; the loss of one or more, or the formation of one or 
more new kinds of pangens underlies (is, in fact) mutation.t As 
de Vries” has stated, this conception formed the basis of the experi- 
ments described in his Mutationstheorie. 
The bearing of this hypothesis on the double primrose-plant 
is almost too obvious to need stating. We may conceive that all 
the unit characters which found expression in both the broad- 
leaved and the narrow-leaved shoot were originally represented in 
either the egg nucleus or the sperm nucleus{ that fused in the 
fertilization. As the fertilized egg developed, they were passed on 
by nuclear and cell division to all the cells of the embryo; and the 
apical meristem, at the time the plumule began to be laid down, 
* Save as suggesting the possibility of artificially inducing mutative variations 
by means of radium rays. 
{ This protoplasmic change is called by de Vries ‘‘premutation’”’. 
tOr both, according to which one of the circumstances above suggested is 
regarded as the initiation of the change. 
