Volume 1
A dictionary of medicine : including general pathology, general therapeutics, hygiene, and the diseases of women and children / by various writers ; edited by Richard Quain ; assisted by Frederick Thomas Roberts and J. Mitchell Bruce.
- Date:
- 1894
Licence: Public Domain Mark
Credit: A dictionary of medicine : including general pathology, general therapeutics, hygiene, and the diseases of women and children / by various writers ; edited by Richard Quain ; assisted by Frederick Thomas Roberts and J. Mitchell Bruce. Source: Wellcome Collection.
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![as a rule, have a tolerance of this poison, so that its effects are best studied in carnivora. Even in these the action is somewhat un- certain. Respiration may be paralysed without general convulsions; the pulse is quickened, from paralysis of the inhibitory action of the pneumogastric nerve on the heart; and the arterial pressure is increased. After very large doses the arterial pressure may be diminished, with paralysis of all parts containing involuntary muscular fibre. Se- cretion is diminished. The pupil is dilated— apparently by a direct influence of the poison on the centres or nervous arrangements in the iris itself, as the effect may be observed even in an eye removed from the head. Hyoscyamine, and Hyoscine, the alka- loids of Hyoscyamus niger, and Daturine, the alkaloid of Datura stramonium, have actions allied to the action of atropine. 5. Digitalin (C27HM015)— the so-called ac- tive principle of Digitalis purpurea, probably a mixture of several bodies. A large dose causes slowing of the heart. If the dose be increased, the heart is arrested in diastole, and will not respond to direct excitation. With medium doses there is a period of acceleration of the heart, but this period may rapidly pass into that of slowness just mentioned. This effect on the heart has not yet been clearly accounted for, and it remains to be decided whether it be due to the influence of the drug on the terminations of the pneumo- gastric, or of the sympathetic, or on the intracardiac ganglia themselves. Coincident with the action on the heart, the smaller arteries are contracted, and the arterial ten- sion is increased. Digitalis would appear to have little effect on involuntary muscle, but it exerts a potent action on voluntary muscle, which, after small doses, becomes feeble in contractile power, while large doses may abolish contractility altogether. 6. Physostigmine, or Eserine, (0]5H21 Ns02)—the active substance of Physostigma venenosum, or Calabar bean. As has been pointed out by Professor Fraser, this alkaloid has an action antagonistic to that of atropine. Sensibility and consciousness remain until death ; the voluntary muscles are paralysed; involuntary muscles are said to show tetanic contractions; respiration is at first acceler- ated, and afterwards slowed; the vessels become alternately dilated and contracted; secretion, especially that from the lachrymal and salivary glands, is increased; and the pupil is contracted. Physostigmine appears to paralyse the anterior cornua of the spinal cord. 7. Curare—a resinous substance, con- taining an alkaloid, Curarine, of the com- position C10HJ5N, obtained from certain parts of South America, and used by the natives of these regions as an arrow-poison. It is probably obtained from certain plants belong- ing to the genera Strychnos and Paullinia. Its distinctive physiological action is abolition of the power of all voluntary movement, in consequence of its action, as was proved by Claude Bernard, upon the peripheral ter- minations of motor nerves—the ' terminal plates ' of muscle. Respiratory movements are arrested as the result of paralysis of the muscles of respiration, but the heart may continue to beat for a considerable time. If artificial respiration be established, the circu- lation may be maintained for several hours, while the animal is completely under the influence of the substance. All the secretions are increased, and the mean temperature falls. 8. Muscarine—the alkaloid of Agaricus muscarius. It causes arrest of the heart's action in diastole, an effect which may be removed by the influence of atropine, thus affording an instance of physiological an- tagonism. In warm-blooded animals mus- carine slows the heart's action; the blood- pressure falls; respiration is first embarrassed, and may be completely arrested ; parts con- taining involuntary muscle are in a state of tetanic spasm; the pupil is contracted ; and secretion is increased. 9. Santonin (C]VHlgO.,)—the neutral crys- talline principle of Artemisia maritima. This drug may cause nausea, vomitmg, halluci- nations, vertigo, and a peculiar state of visual sensation—the field of vision usually appear- ing yellow, but sometimes violet. It is said that the stage of violet rapidly passes into that of yellow, and therefore it is probable that santonin may first excite the retinal fibres sensitive to violet (according to Thomas Young's theory of colour-perception), and afterwards paralyse them. In large doses, santonin causes loss of consciousness, tetanic convulsions, and death. 10. Ergotin—the so-called active prin- ciple of Ergot. It causes contraction of the smaller blood-vessels, contractions of the uterus, and slowing of the pulse; and the animal may die in consequence of arrest of the action of the heart. 11. Quinine (C20H4tN2O2)—one of the al- kaloids of Cinchona. In small doses qvunine accelerates the heart in the warm-blooded animal; in moderate doses it slows it; and in large doses it may arrest it, and cause con- vulsions and death. Research shows that its action is essentially upon the central nervous system. It destroys all microscopic animal organisms, apparently killing vibrios, bacteria, and amoebae; but it seems to be without action on humble organisms belonging to the vegetable kingdom. It arrests the move- ments of all kinds of protoplasm, including those of the colourless corpuscles of the blood. It arrests fermentative processes which depend on the presence of animal or vegetable organisms, but it does not interfere with the action of digestive fluids. 12. Nicotine (C^H^Nj)— the alkaloid of Tobacco. It stimulates and then paralyses](https://iiif.wellcomecollection.org/image/b20415539_001_0078.jp2/full/800%2C/0/default.jpg)
