336 THE POPULAR SCIENCE MONTHLY. 



its gates closed for an unusually long time, and the disease were in its 

 neighborhood. 



The reports of the cholera commission for the German Empire con- 

 tain a large number of proofs of the influence of the locality, particu- 

 larly of the soil, among which I might especially mention the reports 

 of Gunther on the spread of cholera in the kingdom of Saxony, and of 

 Pistor on the government district of Oppeln. Both these investiga- 

 tors, not satisfied with considering only the last visitation of cholera 

 in 1872-'74, have also included within the circle of their inquiry all 

 the outbreaks that have come to knowledge since the appearance 

 of the disease in Europe in 1832. The confirmation of the localistic 

 theory of cholera and other epidemics can no longer be put in ques- 

 tion ; and, if it were the only result reached by the German cholera 

 commission, the money appropriated to the investigation would have 



been well spent. 



We may now ask, What can there be in the soil that can exert so 

 powerful an operation for good or evil upon our health ? To this 

 question, so far as concerns injury to health, the answer may be re- 

 turned that, in all probability, the property is derived from the mi- 

 nute organisms or their products, of which many million individuals 

 can be put within the area of the head of a pin, and which inhabit the 

 porous soil from the surface down to a great depth organisms which 

 are capable of being injurious or harmless, or even useful to us, as we 

 are already acquainted with injurious and harmless and useful plants 

 and animals. They have heretofore been invisible to us, having only 

 just been brought to knowledge, in the course of recent investigations 

 in vegetable and animal physiology and pathology, by means of the 

 microscope and experimental cultivation. A prominent vegetable 

 physiologist, Naegelli, has accurately and clearly described them with 

 direct reference to their hygienic significance in his well-known work, 

 " Die niederen Pilze in ihren Beziehungen zu den Infectionskrankhei- 

 ten und der Gesundheitspflege." Their mysterious presence recalls 

 the ancient belief in invisible spirits that were accustomed to rise out 

 of the earth, float in the water, and cast gloom over the spots haunted 

 by them. Naegelli called a soil that produces or favors epidemics a 

 disease-bearing (Siechhaft), and its opposite a healthful (Siechfrei) 

 soil. We must not conclude that only a locality of the former kind 

 harbors molds and similar lower organisms, and one of the latter kino 

 does not, or that these organisms reach us only from the former and 

 not from the latter ; on the contrary, they are always present every- 

 where. If they sometimes appear deleterious, at other times harm- 

 less, the conviction is forced upon us, either that the same species do 

 not occur universally, or that the same species assume different prop- 

 erties at different places, under different circumstances, and at dif- 

 ferent limes ; that is, that they are only here and there and occa- 

 sionally poisonous. If either is the case, the medium in which tin y 



