the parent without end, each joint being furnished with its proper mouth
and organs of digestion.'"[171]

. . . . . .

"Many ingenious philosophers have found so great difficulty in
conceiving the manner of the reproduction of animals, that they have
supposed all the numerous progeny to have existed in miniature in the
animal originally created; and that these infinitely minute forms are
only evolved or distended, as the embryon increases in the womb. This
idea, besides its being unsupported by any analogy we are acquainted
with, ascribes a greater tenuity to organized matter than we can readily
admit; as these included embryons are supposed each of them to consist
of the various and complicate parts of animal bodies, they must possess
a much greater degree of minuteness than that which was ascribed to the
devils which tempted St. Anthony, of whom 20,000 were said to have been
able to dance a saraband on the point of the finest needle without
incommoding one another."[172]

. . . . . .

"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
locomotion, 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 tube.
Such moving filaments and such rings are described by those who have
attended to microscopic animalculae. This living ring may now embrace or
absorb a nutritive particle of the fluid in which it swims; and by
drawing it into its pores, or joining it by compression to its
extremities, may increase its own length or crassitude, and by degrees
the living ring may become a living tube.

"With this new organization, or accretion of parts, new kinds of
irritability may commence; for so long as there was but one living organ
it could only be supposed to possess irritability; since sensibility may
be conceived to be an extension of the effect of irritability over the
rest of the system. These new kinds of irritability and of sensibility
in conse