drive our
muscles and other organs unless it is supplied with oxygen from the air
to burn it slowly inside our bodies. This oxygen is taken into the
system, in all higher animals, by means of lungs or gills. Now, when we
are working at all hard, we require a great deal of oxygen, as most of
us have familiarly discovered (especially if we are somewhat stout) in
the act of climbing hills or running to catch a train. But when we are
doing very little work indeed, as in our sleeping hours, during which
muscular movement is suspended, and only the general organic life
continues, we breathe much more slowly and at longer intervals. However,
there is this important difference (generally speaking) between an
animal and a steam-engine. You can let the engine run short of coals and
come to a dead standstill, without impairing its future possibilities of
similar motion; you have only to get fresh coals, after weeks or months
of inaction, and light up a fresh fire, when your engine will
immediately begin to work again, exactly the same as before. But if an
animal organism once fairly runs down, either from want of food or any
other cause--in short, if it dies--it very seldom comes to life again.

I say 'very seldom' on purpose, because there are a few cases among the
extreme lower animals where a water-haunting creature can be taken out
of the water and can be thoroughly dried and desiccated, or even kept
for an apparently unlimited period wrapped up in paper or on the slide
of a microscope; and yet, the moment a drop of water is placed on top of
it, it begins to move and live again exactly as before. This sort of
thorough-going suspended animation is the kind we ought to expect from
any well-constituted and proper-minded toad-in-a-hole. Whether anything
like it ever really occurs in the higher ranks of animal life, however,
is a different question; but there can be no doubt that to some slight
extent a body to all intents and purposes quite dead (physically
speaking) by long immersion in water--a drowned man, for example--may
really be resuscitated by heat and stimulants, applied immediately,
provided no part of the working organism has been seriously injured or
decomposed. Such people may be said to be _pro tem._ functionally,
though not structurally, dead. The heart has practically ceased to beat,
the lungs have ceased to breathe, and physical life in the body is
temporarily extinct. The fire, in short, has gone out. But if only