and brought back to its full size, after every
exertion.

For example, this present lecture, whatever its intellectual worth to you,
has a certain physical value to me, which is conceivably expressible by
the number of grains of protoplasm and other bodily substance wasted in
maintaining my vital processes during its delivery. My _peau de chagrin_
will be distinctly smaller at the end of the discourse than it was at the
beginning. By and by, I shall probably have recourse to the substance
commonly called mutton, for the purpose of stretching it back to its
original size. Now, this mutton was once the living protoplasm, more or
less modified, of another animal--a sheep. As I shall eat it, it is the
same matter altered, not only by death, but by exposure to sundry
artificial operations in the process of cooking.

But these changes, whatever be their extent, have not rendered it
incompetent to resume its old functions as matter of life. A singular
inward laboratory, which I possess, will dissolve a certain portion of the
modified protoplasm; the solution so formed will pass into my veins; and
the subtle influences to which it will then be subjected will convert the
dead protoplasm into living protoplasm, and transubstantiate sheep into
man.

Nor is this all. If digestion were a thing to be trifled with, I might sup
on lobster, and the matter of life of the crustacean would undergo the
same wonderful metamorphosis into humanity. And were I to return to my
own place by sea, and undergo shipwreck, the crustacea might, and
probably would, return the compliment, and demonstrate our common nature
by turning my protoplasm into living lobster. Or, if nothing better were
to be had, I might supply my wants with mere bread, and I should find the
protoplasm of the wheat-plant to be convertible into man, with no more
trouble than that of the sheep, and with far less, I fancy, than that of
the lobster.

Hence it appears to be a matter of no great moment what animal, or what
plant, I lay under contribution for protoplasm; and the fact speaks
volumes for the general identity of that substance in all living beings. I
share this catholicity of assimilation with other animals, all of which,
so far as we know, could thrive equally well on the protoplasm of any of
their fellows, or of any plant; but here the assimilative powers of the
animal world cease. A solution of smelling-salts in water, with an
infinitesimal proportion of some other