rease of weight along with the increase of dimension; and is even
visible to our eyes in the elongation of our hair from the colour of its
ends; or when it has been dyed on the head; and in the growth of our nails
from the specks sometimes observable on them; and in the increase of the
white crescent at their roots, and in the growth of new flesh in wounds,
which consists of new nerves as well as of new blood-vessels.

3. Lastly, Mr. Buffon has with great ingenuity imagined the existence of
certain organic particles, which are supposed to be partly alive, and
partly mechanic springs. The latter of these were discovered by Mr. Needham
in the milt or male organ of a species of cuttle fish, called calmar; the
former, or living animalcula, are found in both male and female secretions,
in the infusions of seeds, as of pepper, in the jelly of roasted veal, and
in all other animal and vegetable substances. These organic particles he
supposes to exist in the spermatic fluids of both sexes, and that they are
derived thither from every part of the body, and must therefore resemble,
as he supposes, the parts from whence they are derived. These organic
particles he believes to be in constant activity, till they become mixed in
the womb, and then they instantly join and produce an embryon or fetus
similar to the two parents.

Many objections might be adduced to this fanciful theory, I shall only
mention two. First, that it is analogous to no known animal laws. And
secondly, that as these fluids, replete with organic particles derived both
from the male and female organs, are supposed to be similar; there is no
reason why the mother should not produce a female embryon without the
assistance of the male, and realize the lucina sine concubitu.

IV. 1. I conceive the primordium, or rudiment of the embryon, as secreted
from the blood of the parent, to consist of a simple living filament as a
muscular fibre; which I suppose to be an extremity of a nerve of
loco-motion, as a fibre of the retina is an extremity of a nerve of
sensation; as for instance one of the fibrils, which compose the mouth of
an absorbent vessel; I suppose this living filament, of whatever form it
may be, whether sphere, cube, or cylinder, to be endued with the capability
of being excited into action by certain kinds of stimulus. By the stimulus
of the surrounding fluid, in which it is received from the male, it may
bend into a ring; and thus form the beginning of a tu