In the same report Dr. Bryden continues:
"I will mention one other fact as a result of my observations, namely, that places surrounded by those vast and splendid groves which are occasionally seen, lying in low and probably marshy situations, surrounded by hills, and which, from the mass of decaying vegetation, are very subject to fever in September, October, and November, are seldom visited by cholera, and if it occurs there are but few deaths, while places on high ground, or in what are called fine, airy situations, free from trees and without hills near, so that they are thoroughly ventilated, suffer very much from cholera."
Murray gives a number of instances showing the influence of trees on the spread of cholera. One of these may find a place here:
"The fact is generally believed, and not long ago the medical officer of Jatisgar, in Central India, offered a striking proof of it. During the wide-spread epidemic of cholera in Allahabad, in 1859, those parts of the garrison whose barracks had the advantage of having trees near them enjoyed an indisputable exemption, and precisely in proportion to the thickness and nearness of the shelter. Thus the European Cavalry in the Wellington Barracks, which stand between four rows of mango trees, but are yet to a certain extent open, suffered much less than the Fourth European Regiment, whose quarters were on a hill exposed to the full force of the wind; while the Bengal Horse Artillery, who were in a thicket of mango-trees, had not a single case of sickness; and the exemption cannot be regarded as accidental, as the next year the comparative immunity was precisely the same."[1]
We need not, however, go to India to observe similiar instances of the influence of a certain degree of moisture in the soil favored by woods or other conditions; we can find them much nearer home. In the cholera epidemic of 1854, in Bavaria, it was generally observed that the places in the moors were spared, in spite of the otherwise bad condition of the inhabitants. The great plain of the Danube from Neuburg to Ingolstadt was surrounded by places where it was epidemic, while in the plain itself there were but a few scattered cases. The same thing has been demonstrated by Reinhard, President of the Saxon Medical College. Cholera has visited Saxony eight times since 1836, and every time it spared the northerly district between Pleisse and Spree, where ague is endemic.
In the English Garden at Munich there are several buildings, not sparsely tenanted—the Diana Baths, the Chinese Tower, with a tavern and out-buildings, the Gendarmerie Station, and the Kleinkessellohe. In the three outbreaks of cholera at Munich none of these places have been affected by it. This fact is the more surprising, as three of them comprise public taverns into which the disease germs must have been occasionally introduced by the public; yet there was
- ↑ "Report on the Treatment of Epidemic Cholera," 1869, p. 4.
