134 PROFESSOR RUTHERFORD ON THE 
or unchanged. ~ Thus, when rhubarb is administered, it gives a colour to the © 
dejections similar to that communicated by the bile, and the physician is there- 
fore puzzled to say whether or not rhubarb affects the liver ; yet, by another 
method of research,.it can be shown that rhubarb increases the secretion of 
bile. . Where the substance, as in the case of sodium sulphate, stimulates the — 
intestinal glands, and thus occasions copious dejections of a watery character, 
whereby their colour is diluted, the physician has found it difficult to say 
whether or not there is a variation in the quantity of bile discharged; yet by 
another method, it can be shown that this substance certainly stimulates the 
liver as well as the intestinal glands. Again, in the case of such substances as 
magnesium sulphate and castor oil, which stimulate the intestinal glands but 
not the liver, the physician, although he certainly did not suppose that they 
increase the flow of bile, nevertheless failed to observe the fact—which may be ~ 
shown by another method,—that they diminish the production of bile. Again, 
when a substance excites the liver to produce more bile, but does not excite 
the intestinal glands to pour forth their watery secretion, and as it were wash 
out the bile discharged into the canal, the clinical observer has in the case of 
benzoic acid and its compounds, sodium salicylate, and others, failed to observe 
that they are cholagogues. But again, the clinical observer is unable to say — 
‘whether or not any cholagogue actually stimulates the hepatic cells to produce © 
more bile, or merely excites the muscular fibres of the gall-bladder and bile 
ducts to expel their contents. Yet rational medicine imperatively requires se 
the first of these questions at all events shall receive a definite answer. 
There are two methods—the clinical and the physiological—by which the 
actions of medicinal agents are investigated. On the clinical method, experi- 
ments are made on men and animals in a state of disease, with a view to cure 
the diseased condition ; whereas, on the physiological method, experiments are 
made with drugs on animals and sometimes also on man in a state of health, 
with a view to determine how they affect the bodily system when its action is 
not distorted by the influence of disease. The clinical method is as old as 
medicine itself, but the physiological mode is of comparatively recent date, and 
has grown out of the fact that the clinical method.has proved to have very 
seriously failed—and nowhere more signally than in the case of the liver—to 
furnish the physician with that definite knowledge which is required to bring 
therapeutics even within sight. of the pale of exact science. . 
Of necessity the influence of a drug upon a diseased condition is the ulti- 
matum of pharmacology, and every experiment upon a healthy bodily system, 
whether of man or animal, is merely ancillary to experiments with the drug in 
disease. Therefore, if we discover that a drug stimulates the healthy liver 
of such an animal as a dog, we do not infer that it must also stimulate the 
human liver in health, and still less do we conclude that it must also act thus in 
