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EFFECTS OF NARCOTIC MEDICINES. 
We suppose, then, opium to act first as a sedative. It operates 
slowly , and it is some time before the depression consequent on 
taking a full dose reaches its acme. The symptoms of depression 
advance at the same rate with a large dose as with a small one ; 
but as a small dose can produce only a certain degree of depression, 
its effects, of course, cease as soon as they have arrived at that point. 
A full dose having a much greater sedative power, its operation 
continues much longer, until, by power added to power, the symp- 
toms have attained to a considerable depression. For the opera- 
tion of opium as a stimulant, we thus endeavour to account : — 
The excitement is a reaction of the system consequent on the de- 
pression primarily produced. As the sedative operation of a small 
dose is very soon over, we have an increased action following very 
speedily after the exhibition of the medicine. The vital power is 
ever jealous of a depressing invasion ; it resists, as long as possible, 
the expression , if we may so call it, of a sedative influence (thus 
with a dose of but weak power we perceive no primary sedative 
effect), and as soon as the operation of the medicine is over a 
vigorous reaction obviates its effects. When a full dose of opium 
has been administered, it is a considerable time arriving at the 
maximum of its power ; it goes on gradually overcoming the re- 
sistance attempted by the vital power of the system, till it has quite 
mastered it ; its effects go so far in diminishing or vanquishing 
vital energy, as to destroy the power of reaction, and, instead, we 
have a total exhaustion, torpor, sleep : the fortress is compelled to 
yield to the persevering and continually superadded efforts of its 
enemy. 
With regard to a medium dose, the apparent effects are, first, 
stimulant, then sedative. Here again we suppose a sedative effect 
to commence immediately and primarily, with an intention of con- 
tinuing to increase as long as the strength of the dose will permit. 
The vital energy is here also on the alert; and before any sedative 
influence is perceived, though part of the operation of the medicine 
has already taken place, and when its remaining power is but 
small, a reaction takes place, which continues until the previous 
depression is completely neutralized. The remaining power of the 
medicine which has been put off by the reaction now takes effect, 
though with irresolute force, the rest procured by it being disturbed, 
in consequence of the unremitting efforts of the vital power to 
maintain her authority. We suppose the intermediate reaction to 
occur only when a certain portion of the sedative effect has taken 
place ; in a full dose it is prevented by the remaining power of the 
medicine being very great. 
If we regard the effects of fear as a sedative, we shall find an 
exact analogy existing ; with this difference, — that its full opera- 
