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TRANSACTIONS OF SECTION .D. 859 
9. Experiments with Drugs as a Question of Science.! 
By WitutaM Suarp, F.B.S. 
At the meeting of the British Association for the Advancement of Science, held 
at Nottingham in 1866, a paper was read ‘On the Physiological Action of 
Medicines,’ the subject being the action of medicines when taken in health. 
The experiments already tried were referred to, and suggestions were made 
relative to further experiments (1) on the objects to be pursued, (2) on the mode 
of proceeding, (3) on the utilisation of the results. 
As these experiments have been continued by the author since the date of that 
paper, now twenty-four years ago, it seems to be a duty to make some report to the 
Association. On the present occasion this shall be confined to the conclusions 
arrived at on one part of the question only. ‘To attempt more would occupy too 
much of the time of this meeting. 
Perhaps the Section may be reminded that the primary object of these experi- 
ments is to answer this question in science: What is the action of the substances 
called drugs on the living body of man? 
It is evident that experiments made in order to discover this action must be 
made on persons in health ; for, when drugs are given to the sick, the complications 
arising from the existing disorder make it difficult, and often impossible, to dis- 
tinguish the action of the drug from the effects of the disease. 
Everyone is aware that this enquiry is comparatively a new one, and that as 
yet little is known of it. 
The conclusions arrived at, which are to be laid before the meeting to-day, are 
the results of experiments with different quantities of the same drug. 
They may be briefly expressed as follows :— 
1. The smallest doses used in these experiments have power to act upon the 
living human body. 
2. The commonly received opinion that the actions of drugs are simply increased 
in degree and not altered in character by increasing the dose is an error. 
3. The actions of doses are sufficiently distinct to admit of classification. 
4, This classification has-two divisions. The first contains groups of doses 
arranged as they act upon the same person. The second contains groups of doses 
arranged as they act upon different persons. 
5. Experiments show that several small doses act upon the same person nearly 
in the same manner; these, therefore, form a group. And there are several larger 
doses which act differently from the first group, but in regard to themselves nearly 
in the same manner; these, therefore, form another group. This is the first 
division. 
6. When not only the quantity of the drug but also the person experimented 
upon is varied, a complication is introduced, owing to the varying sensitiveness of 
different persons ; nevertheless a succession of groups of doses may still be observed, 
These groups differ from, and often overlap, those of the first series. This is the 
second division. 
7. Each of the groups of doses in either division has characteristic actions, in 
kind or in degree, which distinguish them from the others. 
8. The actions of a group of certain small doses are directly contrary to the 
actions of another group of certain larger doses, This conclusion is so clearly 
established as applicable to all drugs, and is so new, that the author has felt it 
necessary to give it a name, and has called it Antipraay, ¢.e., contrary action. 
9. There is a group of intermediate doses, between these contrary-acting groups, 
which has both actions in succession. 
10. There is a group of still larger doses, which have the same actions as the 
smallest ones, but differ from them in degree; they act more violently, and their 
action is accompanied with more or less serious complication. 
11. There are yet larger doses, which again act in the contrary direction. 
12. The experiments already tried seem to indicate that between every two 
1 The Paper, with a Supplement, will be published by Messrs. Bell & Sons as 
Essay LVIII. 
3K 2 
