304 Darwin and Pangenesis. [July, 
“ prepotency,” as he terms it) be with the mother or female parent, 
then her or, if a plant, its likeness will be transmitted. 
Now, if we once admit, what is of course quite a matter of 
speculation, namely, that the male and female elements are built 
up of atoms possessing different properties, bone-forming atoms, 
flesh-forming atoms, fat-forming atoms, to speak popularly, it is 
natural to suppose that these atoms when they are distributed 
through the organism may have an attraction for their kind, and 
this the author also assumes, and as a consequence that if there be 
a variation in the constitution of the reproductive elements, there 
will be a tendency to vary in the whole organism, and thus new 
varieties may arise. 
But, finally, if one or both of the sexual elements should be 
deficient in those gemmules, or in the kind of gemmules necessary 
for fertilization of some particular form, so that one or both, instead 
of being “ prepotent,” should be “impotent,” then hybridity is the 
result—that is, the male of one may be impotent with the female of 
another species, or vice versa; or they may be mutually infertile. 
Some of our readers will probably have felt a little difficulty 
in following us through this intricate “provisional hypothesis,” 
for it removes still farther from the reach of our senses the agencies 
by which vital changes are supposed by the author to be brought 
about in animated nature. That naturalists will have to devote 
their attention to this obscure question is, however, quite certain ; 
but the large majority of readers, even those tolerably well ac- 
quainted with biological phenomena, will only see in the “ provisional 
hypothesis” a means of solving a difficult problem by another still 
more difficult of solution. 
First, let us confine ourselves to the physical aspect of the 
question. Perhaps the simplest form of cell known to us is the 
Ameba. This consists of cell-contents probably enclosed in a 
highly elastic cell-wall. The cell-contents comprise a nucleus or 
germ, a nucleolus within the nucleus, and a number of granules 
floatmg in a semi-filuid substance often called “sarcode.” This 
simple cell is already believed to possess in its nucleus and nucleo- 
lus some kind of organs of reproduction; but according to the 
author, it must contain a vast number of gemmules of different 
natures, for it is from such cells as these, im all probability, that 
many higher organisms have been built up. It does not neces- 
sarily follow that such a cell should contain “ gemmules” of all 
kinds needful for the assimilation of the various organic and inorganic 
substances with which higher organisms that will proceed from it 
“by descent” are to be nourished; but what the cell must at 
some time or other have (according to the author’s views) is a 
tendency to vary, else we should come to a standstill at the very 
threshold of “nature’s progression,” and all the beautiful varieties 
