The cholera-germ : when, where, and why infectious / by Gustav Jaeger ; translated and edited by Lewis R.S. Tomalin.

  • Jäger, Gustav, 1832-1917.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: The cholera-germ : when, where, and why infectious / by Gustav Jaeger ; translated and edited by Lewis R.S. Tomalin. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    disease in the host, which is for us the main question; further, there is the injury which is caused to the internal parasite by its own self-poison. The joint effect of these conditions is that its germs cannot develop in the same host, but first require a change of abode, in order to be purged of their self-poison. After these explanatory remarks respecting large parasites, we can turn to consider the minute parasites, especially the animate disease germs. These accurately follow the general rules of parasitism, and display the same contrast between external and internal parasites. 1. The minute external parasites are always capable of infecting, and comprise the germs of the, properly speaking, infectious diseases, such as smallpox, measles, scarlet fever, etc., the bacteria of which, it is true, have partly yet to be discovered. These germs require no change of abode, and are therefore not concerned with external natural conditions, and maybe compared with lice, fleas, and wood-lice, which merely depend on the individual tendency in so far as some only settle on healthy hosts, while others select hosts which are diseased. 2. The internal parasites, especially the intestinal, such as the cholera and typhus bacilli, as also, for instance, the germs of malaria, are not directly infectious; they must pass some time in a different kind of medium from their previous host in order to resume their capacity to infect. 3. The second form of contrast also applies to the minute parasites. The germs of infectious skin diseases are proof against the effects of light and air, i.e., desiccation and light do not injure them. It is otherwise with the internal bacteria. It has been known for some time that the cholera-bacillus is very sensitive to desiccation, and now Professor Buchner, of Munich, has shown by experiments that this bacillus cannot stand the light, and only flourishes in the dark. A zoologist could have confidently predicted that without experiment, and I now assert the same thing of the bacteria of typhus, dysentery, and diarrhoea with vomiting. 4. The internal bacteria possess the same astounding fertility as the intestinal worms, especially those of cholera—the estimate of the number of bacilli in a cubic centimetre of cholera evacuation is ten milliards! To a zoologist this one fact alone