THE HYGIENIC INFLUENCE OF PLANTS. 427 



ninety miles through a barren, treeless plain, we find the cholera every year in 

 its more severe form, the dead and dying lying by the wayside, and trains of 

 vehicles half of whose conductors are dead." 



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 Sep- 

 tember, 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 thor- 

 oughly 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 Jatis- 

 gar, 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 bar- 

 racks had the advantage of having trees near them enjoyed an indisputable ex- 

 emption, 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 Eegiment, 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." ' 



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, Presi- 

 dent of the Saxon Medical College. Cholera has visited Saxony eight 

 times since 1836, and every time it spared the northerly district be- 

 tween 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 Kleinkes- 

 sellohe. 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 

 1 "Report on the Treatment of Epidemic Cholera," 1869, p. 4. 



