WHAT IS A TONIC? 
439 
either case_, while ivaste is necessarily going on_, repair is im- 
perfect or wanting ; and thus parts naturally firm and elastic 
with fulness of structure hound up in them become lax and 
flaccid from the uncompensated loss of their substance. Parts, 
too, of the body, particularly muscles, grow less in bulk and 
compactness when kept inactive, as they so often are during 
disease, and consequently cease to distend the membranes 
which enclose them. In cases of favourable recovery from 
long and exhausting illness, effects of an opposite kind are as 
strikingly observed, the increase in quantity of the tissues, 
and consequent plumping up and distension of parts relaxed 
and yielding. 
The tone of the body, then, is the general firmness and 
elasticity of its parts, and that full contractile power in its 
muscles which we find in them in a condition of high vigour 
and active performance of function. This condition being a 
characteristic of health, to give tone to the body is almost 
identical with giving health to it, — giving it those powers it 
has lost during a course of disease. Let us, then, next consider, 
so far as concerns us, the nature and causes of recovery to 
health, in order that we may better understand the part which 
we look to tonics to play. 
Our bodies are usually in a state of health under the combined 
action of the circumstances to which they are ordinarily 
submitted. If, now, some of these circumstances undergo 
change, ill-health results, as we see, for instance, in the effects 
of food imperfect in quality or quantity, of over-work of mind 
or body, of the unwholesome atmosphere and scanty light 
which pervade so many of the dwellings of the poor in our 
large cities, or of many other modifications of the normal 
circumstances of life sufiiciently obvious. When, however, 
the combination of the circumstances bearing upon our bodies 
has been for a time such as to induce bad health, but is now 
replaced by that which is suited to the maintenance of good 
health in a body already healthy, it is found that, in most 
cases, the bad state of health gives place more or less rapidly 
to a more healthy state. Why it does so may be thus accounted 
for. The common state of the body, that of health, is one 
which has been determined by the operation of the ordinary 
circumstances of life continued from its origin, and one, there- 
fore, which is a true expression of the effects of such circum- 
stances, or, as we usually say of it, it is the natural state. 
On the other hand, any one of the states of ill-health in the 
body has been induced by an unusual combination of circum- 
stances ; and since it is more or less dependent upon such a 
combination for its preservation, the known instability of any 
state of ill-health, as a condition of the body, is a natural con- 
