as the most necessary of all branches of instruction for
themselves and for their children, that which professes to acquaint them
with the conditions of the existence they prize so highly--which teaches
them how to avoid disease and to cherish health, in themselves and
those who are dear to them.

I am addressing, I imagine, an audience of educated persons; and yet I
dare venture to assert that, with the exception of those of my hearers
who may chance to have received a medical education, there is not one
who could tell me what is the meaning and use of an act which he
performs a score of times every minute, and whose suspension would
involve his immediate death;--I mean the act of breathing--or who could
state in precise terms why it is that a confined atmosphere is injurious
to health.

The _practical value_ of Physiological knowledge! Why is it that
educated men can be found to maintain that a slaughter-house in the
midst of a great city is rather a good thing than otherwise?--that
mothers persist in exposing the largest possible amount of surface of
their children to the cold, by the absurd style of dress they adopt, and
then marvel at the peculiar dispensation of Providence, which removes
their infants by bronchitis and gastric fever? Why is it that quackery
rides rampant over the land; and that not long ago, one of the largest
public rooms in this great city could be filled by an audience gravely
listening to the reverend expositor of the doctrine--that the simple
physiological phenomena known as spirit-rapping, table-turning,
phreno-magnetism, and by I know not what other absurd and inappropriate
names, are due to the direct and personal agency of Satan?

Why is all this, except from the utter ignorance as to the simplest laws
of their own animal life, which prevails among even the most highly
educated persons in this country?

But there are other branches of Biological Science, besides Physiology
proper, whose practical influence, though less obvious, is not, as I
believe, less certain. I have heard educated men speak with an
ill-disguised contempt of the studies of the naturalist, and ask, not
without a shrug, "What is the use of knowing all about these miserable
animals--what bearing has it on human life?"

I will endeavour to answer that question. I take it that all will admit
there is definite Government of this universe--that its pleasures and
pains are not scattered at random, but are distributed in a