[67] _Essays on Heredity_, p. 104. Weismann's theory is clear, simple
and convenient, but incomplete; for, unlike Darwin's theory of
pangenesis, it scarcely attempts any real explanation of the extremely
complex potentialities possessed by the reproductive elements. Perhaps
we might retain Darwin's self-multiplying gemmules without supposing
them to be thrown off by the cells, which will no longer be credited
with _two_ modes of multiplication. These minute germs or gemmules may
have been evolved by natural selection playing upon the sample germs
that achieve development; and they may exist either separately, or
(preferably but perhaps not invariably) in aggregates to form Weismann's
germ-plasm.
[68] _Contemporary Review_, Dec., 1875, p. 88.
[69] _Variation of Animals and Plants under Domestication_, ii. 286.
[70] _Variation of Animals and Plants under Domestication_, ii. 388,
398, 367; _Life and Letters_, iii. 44.
[71] _Contemporary Review_, Dec., 1875, pp. 94, 95.