STUDIES OF MATTER AND LIFE. 
157 
The phenomena of the nourishment and growth of plants and 
animals depend upon actions of this sort brought about by the 
wave motions of heat, light, electricity, and so forth. Repro- 
duction is, as Claude Bernard explains, intimately connected 
with nutrition. A particle capable of germination or growth 
receives an impulse from a particle of an opposite sex, that is, 
of one in a different molecular condition, and development is 
stimulated and caused to take place so as to repeat with minor 
variations the parent forms. The well-known facts of inheri- 
tance show that, although the female germ and the stimulating 
male element — the ovule and pollen grain of a plant, for ex- 
ample— are very minute, they are big enough to contain, in some 
form, .or way, forces which cause all fresh matter that is assimi- 
lated to arrange itself so as to reproduce a series of parts repeating 
for generations with marvellous fidelity the parental types. 
The same thing is noticed with animals in which the same 
species or the same race is reproduced from one generation to 
another with remarkable accuracy, extending to minute and 
often unexpected detail. For information on this subject the 
reader must be referred to the works of Darwin and other 
writers. What we have now to consider is whether the germ 
particles and sperm particles can possibly be conceived to con- 
tain enough molecules built up in definite patterns, so that, as 
Darwin in his theory of Pangenesis supposes, they can supply 
parents enough to enable us to regard each portion of a complex 
organism, plant or animal, as composed of their lineal descend- 
ants. “If,” says Darwin, “one of the simplest Protozoa be 
formed, as appears under the microscope, of a small mass of 
homogeneous gelatinous matter, a minute atom thrown off from 
any part, and nourished under favourable circumstances, would 
naturally reproduce the whole ; but if the upper and lower 
surfaces were to differ in texture from the central portion, then 
all three parts would have to throw off atoms, or gemmules, 
which, when aggregated by mutual affinity, would form either 
buds or the sexual elements. Precisely the same view may be 
extended to one of the higher animals, although in this case 
many thousands of gemmules must be thrown off from the 
various parts of the body.” * 
To compose a plant under this theory, the seed must contain 
gemmules which attract suitable matter to form root-fibres ; 
other gemmules that in like way cause cells to grow and ag- 
gregate to make a fibrous stem, others to supply the sap, others 
to cause the growth and development of the leaves, flowers, and 
finally to supply the ovule and the pollen with a complete set of 
gemmules to carry on the process from one generation to 
* 11 Animals and Plants under Domestication/’ vol. ii. chap, xxvii. 
