Page:Tropical Diseases.djvu/504

462 adduced clearly point to water as a principal medium for the diffusion of the cholera germ. The virus contained in the dejecta.— Evidence equally conclusive tends to show that the germ on being swallowed by man multiplies in his alimentary canal, and, on being voided in the dejecta, subsequently finds its way by a route more or less direct to water again, in which, under favourable conditions, it continues still further to multiply. An illustration, amounting almost to proof, of the fact that the germ of cholera is contained in the stools of cholera patients is supplied by Macnamara. Some of the characteristic rice-water discharge from a cholera patient got mixed accidentally with a few gallons of water. This was exposed to the sun for twelve hours. Early the following morning 19 persons each drank about an ounce of the mixture. Within thirty-six hours 5 of these 19 persons were seized with cholera.

Conditions of infection are complex.— It is evident that the ingestion of the germ is a necessary condition for the production of the disease, but there are many facts which render it equally evident that this is not the only condition. Were it the only condition, then every one of those individuals referred to by Macnamara would have sickened. What the other necessary conditions may be it is, in the present state of knowledge, impossible to say.

There is reason to believe that not only are the conditions complicated as regards the susceptibility of the individual, but also that they are equally complex as regards the germ itself in relation to its pathogenic, proliferating, and diffusing properties. The germ of cholera.— Early views.— Since European pathologists first directed their attention to the subject, many views have been entertained as to the exact nature of the cause of cholera. Some of these views were of the most fantastic description. Mysterious atmospheric and telluric conditions were invoked, and only a very few years ago superstitious notions worthy of the Middle Ages were freely ventilated, even in high places and by educated minds.