ater. The nature of
the particles given off by odorous bodies which act on the
nerve-endings of the organs of smell of animals, is remarkable. They
are volatile; that is to say, they are thrown off from their source
and float in the air in a state of extreme subdivision. Unlike the
particles which act upon the nerves of taste, they are not
necessarily soluble in water, and though often spread through and
carried by liquids, are in fact rarely dissolved in water. The
dissolved particles which act upon the nerves of taste can be
distinguished by man into four groups--sweet, sour, bitter, and
saline. But no such classification of "smells" is possible. As a rule
mankind confuses the "taste" of things with their accompanying
"smell." The finer flavours of food and drink not included in the four
classes of tastes are really due to odoriferous particles present in
the food or drink, which act on the terminations of the olfactory
nerves in the recesses of the nose, and excite no sensation through
the nerves of taste.

The part of the brain from which the nerves of smell arise is of
relatively enormous size in the lower vertebrates--as much as one
fifth of the volume of the entire brain in fishes--a fact which seems
to indicate great importance for the sense of smell in those forms.
Even in the mammals (the hairy, warm-blooded, young-suckling beasts)
the size of the olfactory lobes of the brain and of the olfactory
nerves, and the labyrinthine chambers of the nose on which the nerves
are spread, is very large, as one may see by looking at a mammal's
skull divided into right and left halves. And it seems immoderately
large to us--to man--because, after all, so far as our conscious lives
are concerned, the sense of smell has very small importance. Yet man
has a very considerable set of olfactive chambers within the nostrils
and has large olfactory nerves. Not rarely men and women are found who
are absolutely devoid of the sense of smell, and the same thing occurs
with domesticated cats and dogs. In these cases the olfactory lobes of
the brain are imperfectly developed. It is found that men in this
condition suffer but little inconvenience in consequence. We are able,
through their statements, to ascertain what parts of the savoury
qualities of food and drink belong to taste and what to smell. Such
individuals do not perceive perfumes, the bouquet of wine, or the
fragrance of tobacco, nor can they appreciate the artistic efforts o