ncts, independently of
those of its parents; and the principle of inheritance at corresponding
periods of life renders this possible.

This principle is, indeed, in one way so obvious that it escapes attention.
We possess a number of races of animals and plants, which, when compared
with each other and with their parent-forms, present conspicuous
differences, both in the immature and mature states. Look at the seeds of
the several kinds of peas, beans, maize, which can be propagated truly, and
see how they differ in size, colour, and shape, whilst the {76} full-grown
plants differ but little. Cabbages on the other hand differ greatly in
foliage and manner of growth, but hardly at all in their seeds; and
generally it will be found that the differences between cultivated plants
at different periods of growth are not necessarily closely connected
together, for plants may differ much in their seeds and little when
full-grown, and conversely may yield seeds hardly distinguishable, yet
differ much when full-grown. In the several breeds of poultry, descended
from a single species, differences in the eggs and chickens, in the plumage
at the first and subsequent moults, in the comb and wattles during
maturity, are all inherited. With man peculiarities in the milk and second
teeth, of which I have received the details, are inheritable, and with man
longevity is often transmitted. So again with our improved breeds of cattle
and sheep, early maturity, including the early development of the teeth,
and with certain breeds of fowl the early appearance of secondary sexual
characters, all come under the same head of inheritance at corresponding
periods.

Numerous analogous facts could be given. The silk-moth, perhaps, offers the
best instance; for in the breeds which transmit their characters truly, the
eggs differ in size, colour, and shape;--the caterpillars differ, in
moulting three or four times, in colour, even in having a dark-coloured
mark like an eyebrow, and in the loss of certain instincts;--the cocoons
differ in size, shape, and in the colour and quality of the silk; these
several differences being followed by slight or barely distinguishable
differences in the mature moth.

But it may be said that, if in the above cases a new peculiarity is
inherited, it must be at the corresponding stage of development; for an egg
or seed can resemble only an egg or seed, and the horn in a full-grown ox
can resemble only a horn. The follo