Physiology and histology of the cerebral convolutions : Also, Poisons of the intellect / by Chas. Richet. Tr. by Edward P. Fowler, M. D.

  • Richet, Charles, 1850-1935.
Date:
1879
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Licence: Public Domain Mark

Credit: Physiology and histology of the cerebral convolutions : Also, Poisons of the intellect / by Chas. Richet. Tr. by Edward P. Fowler, M. D. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    this difference of resistance to poisonous agents is not yet explained. We know that belladonna and atropine, so poi- sonous to man, have but a slight effect on a rabbit, and that a dose sufficient to kill ten robust men is hardly enough to kill a rabbit. Morphine, the principal and most energetic substance contained in opium, so far as its action on man is con- cerned, has very nearly the same effect as crude opium. In medicine we prescribe them indifferently, so that we may comprehend them both in a common description. The sleep-producing power of opium is supposed to be derived from its action on the cerebral circulation. It is not yet certain that this is the true cause, but it is the result of much laborious investigation. On trephining the skull and inspecting the cerebral surface in animals, we find that the aspect varies accord- ing to the size and condition of the blood-vessels which cover the brain. Sometimes the surface is purple, swollen, and covered with a network of dilated blood-vessels, this is cerebral congestion. At other times it is pale, depressed, and the capillaries can hardly be distinguished, there is a deficiency of blood or aneemia of the brain. Now, it is found that the circulation of the retina of the eye is the image of the cerebral circulation, so that when the brain is congested, the eye is also congested, and vice versa. This furnishes a method of diagnosis by means of the ophthal. moscope, but there is another way of judging of the con- dition of the blood-vessels of the eye. The circular and contractile opening in the iris, the pupil, which contracts in the light and dilates in the dark, is always contracted when the brain is congested, and always dilated when the brain is anaemic, provided the observation is not made with the patient placed in a dazzling light, nor in a darkness too profound. Then we might suppose that, since in normal sleep, as in the sleep produced by opium, the pupil is very much con- tracted, the brain is in a state of congestion in both cases,