443 
union of two such masses constitutes the essential part of the gener- 
ative act. In the Cryptogamia, a vibratile antheroid particle enters 
a germ cell, and finds this last filled with a mass of molecules which, 
on receiving the stimulus it imparts, assumes the power of growth. 
It is the same among the Phanerogamia, when the germ-cell is 
impregnated by the pollen tube. In all these cases it is necessary 
to remember that the protoplasm is a mass of molecules ; that a 
spore is another mass of molecules ; that sporules are molecules ; that 
antherozoids are only molecules with vibratile appendages ; and that 
the so-called germinal matter of the ovule is also nothing but a mass 
of molecules. Cell-forms are subsequent processes, and once pro- 
duced may multiply endogenously, by gemmation or cleavage; all 
that is here contended for is, that the primary form is molecular, and 
that the force-producing action in it is a molecular force. 
In animals, as in vegetables, every primary act of generation is 
brought about by the agency of molecules. The Protozoa entirely 
consist of mere molecular gelatiniform masses, in which it has never 
been pretended that a cell wall or central cell exists. And yet such 
masses have the power of independent motion, and of multiplying by 
gemmation. Considerable discussion has occurred as to whether, 
among Infusorians, there is a union of sexes or a conjugation similar 
to what occurs among the Protophyta ; but in either case, it is by 
molecular fusion that the end is accomplished. In the higher classes 
of animals there are male elements, consisting of molecules, generally 
with, but sometimes destitute of, vibratile filaments, and female ele- 
ments, composed of the yolk within the ovum, containing a germinal 
vesicle or included cell. Both spermatozoid and germinal vesicle 
are dissolved in the molecules of the yolk, which then, either wholly 
or in part, by successive divisions and transformations, constitute a 
germinal mass out of which the embryo is formed. Here, as in 
plants, it is necessary to remember that the spermatozoids, the yolk, 
and the germinal mass, are all composed of molecules, and that these, 
combining together, form the nuclei, cells, fibres, and membranes 
which build up the tissues and organs of the organism. It is not 
from either the male or the female element that the embryo is formed. 
The supporters of an exclusive cell doctrine have endeavoured to 
show that there is always a direct descent either from the wall of the 
ovum or from the germinal vesicle as its nucleus. Thus some con- 
sider that the vitelline membrane sends in partitions to divide the 
