Those who wish for farther information upon this subject may consult the chapter on “The Physiological Causes and Phœnomena of Sudden Death,” in my work on “Medical Jurisprudence,” Vol. 2. p. 16.
[152]. Hippocrat. de Diœta. lib. iii. et alibi passim.
This predilection of the ancients for Emetics is the more extraordinary, as they were acquainted with those only which were of the most violent and unmanageable description; the Veratrum or White Hellebore, was sometimes fatal.
[153]. Few discoveries in physiology have thrown greater light upon this important subject than that of M. Majendie, published in his Journal De Physiologie Experimentale, (1er numero—Janvier, 1821) in a paper entitled, “Memoir sur le Méchanisme de L’Absorption.” The results contained in this essay are the more interesting to me, as they were read at the Academy of Sciences at Paris, some time after the publication of the Third Edition of my Pharmacologia, and it will be observed, in what a satisfactory manner they confirm the views which I offered at that time, respecting the influence of venesection in accelerating the absorption of Mercury. In the Fourth Edition (published in October, 1820, p. 115,) these views were farther extended, and as I could not have been influenced by the experiments of M. Majendie, which were not published until some time afterwards, it is very fair to conclude, that when two persons arrive at the same result by different trains of investigation, such a result must be correct. The conclusions established by the experimental inquiries of M. Majendie, with regard to absorption, appear to me to be so important, in reference to the object of the present work, that I shall pause, in this place, for the purpose of furnishing the reader with a short account of them. M. Majendie states, that while performing the experiment of injecting warm water into the veins of a living animal, he first conceived the idea of observing what effects would be produced upon the function of absorption by the artificial plethora, thus occasioned; having accordingly injected a quantity of water into the venous system of a middle-sized dog, he introduced a small portion of an active substance, whose effects were well known, into his side, when he was surprised to find that its usual operation was not manifested until after an interval much longer than usual; the same experiment was afterwards repeated upon another animal, and with similar results. In a third experiment, as much water (about two pounds) was injected, as the animal could sustain without destruction, in which case the poisonous substance produced no effect whatever, the powers of absorption appearing to be entirely suspended: and having waited during half an hour for the occurrence of those symptoms which, under ordinary circumstances, would have manifested themselves in two minutes, M. Majendie concluded that if vascular congestion be the cause of the suspension of absorption, the function ought to be restored by the removal of this artificial condition, an opinion which he proceeded to verify by experiment; the jugular vein of the animal, under trial, was accordingly opened, and the ingenious operator had the satisfaction to observe the effects of the poison gradually developing themselves in proportion as the blood flowed. M. Majendie next proceeded to confirm the truth of his position, by an experiment, the converse of those above related; an animal was bled, to the amount of about half a pound, and the poisonous substance applied to the pleura of the animal, as in the foregoing experiments, when it appeared that those effects which, under ordinary circumstances, were not evident until after a period of twelve minutes, manifested themselves after an interval of only thirty seconds. In order to shew that these results actually arose from vascular distention, and not from the artificial state of dilution in which the blood was placed, M. Majendie instituted the following experiment: a considerable quantity of blood was drawn from the vein of a dog, and replaced by a similar quantity of warm water, after which a measured quantity of Nux Vomica in solution was introduced into the side, when the poisonous effects were found to take place with the same rapidity as if the blood had not been mixed with water.
[154]. The practical application of this fact may be useful, and digestion, in certain cases, may be thus promoted by the simple expedient of changing the quality of our bread.
[155]. Since the publication of this opinion, in the 5th edition of the Pharmacologia, Dr. Hamilton has honoured me by a letter on the subject, but I am still bound to confess that my sentiments remain unaltered.
[156]. The Melampodium, or Black Hellebore, was recommended as an agent of this description in the strongest terms, by Mead; Savin (Juniperus Sabina) is another vegetable which has been generally considered as a specific Emmenagogue; with some authors, the Rubia Tinctorum, Madder; with others, the Sinapis alba have been regarded as remedies of this nature; and lately Polygala Senega has been extolled by the American practitioners; in modern times, however, few substances have been more confidently recommended as uterine stimulants than the Secale Cornutum, or Ergot, but of which I have no practical knowledge.
[157]. Saline bodies would appear to be the peculiar stimuli of these organs, the principal use of which is to separate such saline matter from the blood, as would otherwise accumulate in the system. That these saline diuretics actually pass off by the kidneys, may be satisfactorily shewn by an examination of the urine, in which the bodies in question may be chemically detected. Let any person swallow several doses of Nitre, taking care that the bowels are not disturbed by the medicine, and he will find by dipping some paper into his urine, and afterwards drying it, that it will deflagrate, and indicate the presence of nitre.
[158]. The Secondary Diuresis which sometimes takes place under such circumstances, and succeeds Catharsis, may offer an apparent exception to this law; but this must not be confounded with that which is the result of a Primary action upon the urinary organs by the absorption, and consequent contact, of a specific Stimulant.
[159]. Certain mineral waters, containing cathartic salts in a state of extreme dilution, if insufficient to excite the bowels, sometimes pass off by the kidneys; an effect which can always be prevented by accompanying their exhibition with some laxative.