Long after the Renaissance, the practice of medicine was still under the influence of magic. Whatever things were rare and precious were held to be good against disease—gold, amber, coral, pearls, and the dust of mummies; whatever took strange forms of life—toads, earthworms, and the like; whatever looked like the disease, after the doctrine of signatures—pulmonaria for the lungs, because the spots on its leaves were like tubercle, a kidney-shaped fruit for the kidneys, a heart-shaped fruit for the heart, and yellow carrots for the yellow jaundice. Among the drugs in the 1618 Pharmacopœia are cranium humanum, mandibula lucii, nidus hirundinum, sericum crudum, linum vivum, and pilus salamandræ. In the Pharmacopœia of 1667 are exuviæ serpentis, telæ aranearum, saliva jejuni, cranium hominis violentâ morte extincti, and worse obscenities.
Soon after the publication of this Pharmacopœia, on 14th February 1685, King Charles II. died; and in the Library of the Society of Antiquaries there is a manuscript account in Latin, by Dr. Scarbrugh, how the case was treated. The King had sixteen physicians, and nine consultations in five days; and to say "everything was done that was possible" gives no idea of the vigour of the treatment. Finally, the day he died, they gave him, eleven of them in consultation—totus medicorum chorus ab omni spe destitutus—they gave him, as more generous cardiacs, the lapis Goæ, and the Bezoar-stone. The lapis Goæ was a dust of topaz, jacinth, sapphire, ruby, pearl, emerald, bezoar, coral, musk, ambergris, and gold, all made into a pill and polished; and the bezoar is a calculus found in the intestines of herbivorous animals. Half a century later, the Pharmacopœia of 1721 still included ants' eggs, teeth, lapis nephriticus, and other horrors; and in the Pharmacopœia of 1746, though the dust of Egyptian mummies was ruled out, vipers and wood-lice were retained.
Certainly these "last enchantments of the Middle Ages" were slow to depart. Clinical observation, anatomy, and pathology, had all failed to bring about a right understanding of the actions of drugs. It was the physiologists, not the doctors, who first formulated the exact use of drugs; it was Bichat, Magendie, and Claude Bernard. That is the whole meaning of Magendie's work on the upas-poison and on strychnine, and Claude Bernard's work on curari and digitalis. Of these four substances, two only are of any use in practice; yet Magendie's study of strychnine[41] was of immeasurable value, not so much because it gave the doctors a "more generous cardiac," though that was a great gift, but because it revealed the selective action of drugs. Contrast his account of strychnine with Ambroise Paré's story how they tested the bezoar-stone on the thief instead of hanging him; contrast Bernard's chapter on curari with Dr. Scarbrugh's notes on the King's death, with all the Crown jewels inside him: you are in two different worlds. The selective action of drugs—the affinity between strychnine and the central nerve-cells, between curari and the terminal filaments of the motor nerves—that was the revolutionary teaching of science: and it came, not by experience, but by experiment.
Take Professor Fraser's address on "The Action of Remedies, and the Experimental Method" at the International Medical Congress in London, 1881:—
"The introduction of this method is due to Bichat; and, by its subsequent application by Magendie, pharmacology was originated as the science we now recognise. Bichat represents a transition state, in which metaphysical conceptions were mingled with the results of experience. Magendie more clearly recognised the danger of adopting theories, in the existing imperfections of knowledge; and devoted himself to the supplementing of these imperfections by experiments on living animals. The advantages of such experiments he early illustrated by his investigation on the upas-poison; and afterwards by a research on the then newly-discovered alkaloid, strychnia.... He demonstrated the action of this substance upon the spinal cord, by experiments upon the lower animals, so thoroughly, that subsequent investigations have added but little to his results."
Or take Professor Fraser's account of digitalis:—
"It was introduced as a remedy for dropsy; and, on the applications which were made of it for the treatment of that disease, a slowing action upon the cardiac movements was observed, which led to its acquiring the reputation of a cardiac sedative. Numerous observations were made on man by the originators of its application, by Dr. Sanders and many other physicians, in which special attention was paid to its effects upon the circulation; but no further light was thrown upon its remarkable properties, with the unimportant exception that in some cases it was found to excite the circulation. It was not until the experimental method was applied in its investigation, in the first instance by Claude Bernard, and subsequently by Dybkowsky, Pelikan, Meyer, Boehm, and Schmiedeberg, that the true action of digitalis upon the circulation was discovered. It was shown that the effects upon the circulation were not in any exact sense sedative, but, on the contrary, stimulant and tonic, rendering the action of the heart more powerful, and increasing the tension in the blood-vessels. The indications for its use in disease were thereby revolutionised, and at the same time rendered more exact; and the striking benefits which are now afforded by the use of this substance in most (cardiac) diseases were made available to humanity."
Or take Sir T. Lauder Brunton's account of the action of nitrite of amyl in angina pectoris:—
"The action of nitrite of amyl in causing flushing was first observed by Guthrie, and Sir B. W. Richardson recommended it as a remedy in spasmodic conditions, from the power he thought it to possess of paralysing motor nerves. In the spring of 1867 I had opportunities of constantly observing a patient who suffered from angina pectoris, and of obtaining from him numerous sphygmographic tracings, both during the attack and during the interval. These showed that during the attack the pulse became quicker, the blood-pressure rose, and the arterioles contracted.... It seemed probable that the great rise in tension was the cause of the pain, and it occurred to me that if it was possible to diminish the tension by drugs instead of by bleeding, the pain would be removed.
"I knew from unpublished experiments on animals by Dr. A. Gamgee that nitrite of amyl had this power, and therefore tried it on the patient. My expectations were perfectly answered. The pain usually disappeared in three-quarters of a minute after the inhalation began, and at the same time the pulse became slower and much fuller, and the tension diminished."