The doctrine of evolution in its application to pathology / by William Aitken.

  • Aitken, William Henry, Sir, 1825-1892.
Date:
1886
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Licence: Public Domain Mark

Credit: The doctrine of evolution in its application to pathology / by William Aitken. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    tions no more is known than of the periodical paroxysms of ague. The body, in its diseases as well as in its functions observes a prmciple of periodicity ; its elements pass through prescribed cycles of changes ; and the diseases of nature are subject to similar variations * But if the latent cause of epidemics cannot be discovered, the mode in which they operate may be investigated. The laws of its action may be determined by observation, as well as the circumstances in which epidemics arise, or by which they may be controlled. As an^ instance of slow but progressive evolution of an epidemic, there can be none more conclusive than in the facts recorded by Dr. Farr, in the work already referred to, as to cholera. It has been established by observa- tion that cholera is most fatal in the low [lying] towns and in the low parts of London, where, from various causes, the greatest quantity of organic matter is in a state of chemical action ;f and it may be admitted that cholera varying in intensity with the quantity is the result of some change in the chemical action of this matter, whether that change is spon- taneous or the result of a zj^motic matter from beyond the seas, and its diffusion is consonant with what is known of the etiology of other diseases. | An important discovery was also made in 1832, when it was found that cholera in its worst forms was preceded by ■diarrhoea, and that this diarrhoea was in some cases of a mild form, in others a first stage of the disease. Now, to arrest this diarrhoea is to prevent cholera, as to extinguish a spark is to prevent a conflagration. It further appears that the deaths from cholera and diarrhoea had increased in London in 1842, that they had increased still more in 1846, when the potato crop M^as blighted, and in 1849 this gradual increase culminated in the evolution of epidemic cholera. § This diarrhoea was shown to be evidently a variety of cholera, proving fatal chiefly to young children and to old people. This evolution was itself gradual and progressive. It occupied a period of seven years, and it is a fact well worthy of attention, that after the temperature of the Thames had risen above 60°, diarrhoea increased, cholera and dysentery became prevalent, and disappeared as the temperature subsided. The cholera reached London in the new epidemic form about October, 1849 ; it prevailed through the winter ; and destroyed 94 lives in the second week of January, 1850, when the tem- perature of the Thames was 37°; it declined rapidly through * Vital Statistics, by Dr. WiUiam Farr, M.D., C.B., F.R.S., 1885, p. 317. t Ihid., p. 349. X Ibid., p. 364. § Ibid., p. 383.