ON THERAPEUTICS. 
659 
The dose is another important consideration, too lightly es¬ 
timated. Not only is the age of the patient to be taken into 
account, but the continuance of the medicinal effect. Generally 
we require the action of a drug to be apparent for some time, 
and to exist for that time without cessation. To gain this object 
very small doses, frequently repeated, are indispensable. No 
definite statement can be made of the number of times in the 
dav the medicine should be administered, nor indeed of the 
precise quantity of the agent to be given, but just enough 
should certainly be exhibited to produce the desired effect, 
and repeated sufficiently often to avoid any positive inter¬ 
ruption to the action. Large doses are administered only 
when powerful and evanescent action is desired. It is 
much to be feared that we are in the habit of exhibiting 
medicines in quantities fixed by custom, rather than deter¬ 
mined by individual judgment, and according to the exi¬ 
gencies of the case. 
With this preliminary and somewhat discursive review of 
the causes by which medicinal effects are modified, we pass 
to the consideration of the agents included in our three 
divisions, in the attempt to justify our system of classification, 
by adducing the admitted properties of drugs as illustrations. 
It would unnecessarily detain us to examine the constitution 
of the various agents, or their preparation, or doses; for 
ample information on all these points, we refer to Morton’s 
c Veterinary Materia Medica,’ modestly called a 6 Manual * 
by its author. 
The application of medicines in the treatment of disease 
requires an acquaintance with its agents, and a knowledge of 
this we have a right to consider is possessed by our readers. 
Upon this assumption, we propose to discuss the actions of 
the various classes and sub-classes into which we have divided 
medicinal substances, with the view to ascertain how far our 
employment of certain drugs may be consistent with our 
knowledge of the science of pathology. 
At the outset, we desire to develope a general plan of action 
in curative treatment. 
First. It is important to ascertain the “ actual and pre¬ 
dominant element,” in the disease to be treated ; nor is this at 
all times so obvious as might be imagined. Nervous ex¬ 
citement may exist with extreme debility ; and directly de¬ 
pressing means, that might be employed to lessen this excite¬ 
ment, would be opposed to true principles. The predominant 
element in such a case is fC anaemia,” or more expressively, 
“ general debility,” and must be met by agents which excite 
and modify action, and not by those which depress: this 
