WHAT IS A TONIC? 
443 
cited^ have very powerful stimulating effects^ in comparison 
with the necessarily slight nutritive effects they can produce, 
blow those substances which are remarkable for their stimu- 
lating effects have received generally the name of stimulants ; 
in consequence of which the great mistake, so very common, 
has been caused, of looking upon other articles of food as 
nutrients only, through which very unsatisfactory ideas have 
been held, and are held still, of the relative nature of foods and 
stimulants. The conclusion at which we must arrive is this, that 
a substance, medicinal or other, may be both a stimulant and a 
nutrient, or what many would call a food ; for a very general 
definition of food makes it a substance which can nourish the 
body with its own matter. 
We trust that our readers will now be prepared to under- 
stand how it is that morphia (the essential ingredient of 
opium), or a suitable portion of brandy or wine, may act like 
meat-soup in exciting the powers of life in certain cases, 
although there can hardly be a doubt in the mind of any one 
familiar with such matters, that the soup alone supplies to any 
extent material wherewith to compensate the waste ” going 
on in the body, — that they will understand that it is because 
all three agents may serve as stimulants, though they may not 
all be nutrients. 
We come now to the relations and distinctions which may 
exist between tonics and food, and tonics and stimulants. To 
give tone is to give power to the body ; to nourish is also to 
give power. While, however, the result of either of the two 
actions, — giving tone and nourishing, — is the same, the mode 
of giving power to the body is different. For, whereas, when 
a substance nourishes, it serves itself as material for the repair 
of the structures of the body — the muscles, and nerves, and 
glands, and blood, — which are, it is plain, the source of power 
in the body, a substance, when it is said to give tone, or to be 
a tonic, does not serve as nutriment itself, but it aids the pro- 
cesses of assimilation of nutritive matters by the system, — it 
helps to cause the taking up by the body of sources of power, 
as found in nutrients. 
The same substance may possess both the properties of a 
nutrient and of a tonic ; it may not only be able to give itself 
for assimilation into the body, but may also help to cause other 
substances to be thus taken up as nutrients. Now, with such 
a substance, just as with those which are both food and 
stimulants, the practice seems to be to call it a food or a 
tonic according as the one or other property predominates. 
For example, cod-liver oil and the various medicinal prepara- 
tions of iron nourish ; but since they possess such very great 
tonic power they are called tonics rather than foods. 
