nimal, and we may as well say, in each of its blood corpuscles, and in
the last instance, in each of its molecules, the respective animal
species is fully represented, as to its odorant speciality, under both
aspects of scent and smell.

We have, then, on the one side, the fact before us that wherever we meet
in the animal kingdom with difference of shape, form, and construction,
so different as to constitute a class, a genus, or a family of its own,
there we meet at the same time with a distinct and specific scent and
smell. On the other hand, we know that these specific odours are
invariably interblended with the very life-blood of the animal. And
lastly, we know that these specific odours cannot be accounted for by
any agents taken up in the shape of food from the outer world. We are,
then, driven to the conclusion that they are properties of the inner
animal; that they, in other words, pertain to the specific protoplasm
of the animal concerned.

And thus our conclusion attains almost certainty, when we remember that
it stands the crucial test of experiment--that we need only decompose
the blood in order to find there what we contend to be an essential
ingredient of it.

I must now say a few words in explanation of the term protoplasm.
Protoplasm is a soft, gelatinous substance, transparent and homogeneous,
easily seen in large plant-cells; it may be compared to the white of an
egg. When at rest all sorts of vibratory, quivering and trembling
movements can be observed within its mass. It forms the living material
in all vegetable and animal cells; in fact, it is that component of the
body which really does the vital work. It is the formative agent of all
living tissues. Vital activity, in the broadest sense of the term,
manifests itself in the development of the germ into the complete
organism, repeating the type of its parents, and in the subsequent
maintenance of that organism in its integrity and both these functions
are exclusively carried on by the protoplasm. Of course, there is a
good deal of chemical and mechanical work done in the organism, but
protoplasm is the formative agent of all the tissues and structures.

Of tissues and structures already formed, we may fairly say that they
have passed out of the realms of vitality, as they are destined to
gradual disintegration and decay in the course of life; it is they that
are on the way of being cast out of the organism, when they have once
run t