298 Cholera in Relation to Cei^tain Physical Phenomena. [part i. 



such as the oases in the Sahara, the unfitness may be only apparent, and, on closer 

 inquiry, .conditions may be demonstrated calculated to produce the result. In others, 

 however, no satisfactory explanation can be afforded. The telluric origin of the cause 

 producing the symptoms of malarial poisoning is not, however, on this account doubted? 

 and if this be so there is no sufficient reason for doubting the telluric origin of the 

 cause of cholera in similar exceptional cases.* 



Not only do we observe marked parallelism between cholera and malaria in the 

 capriciousness manifested by the apparently very opposite conditions of soil in which 

 the diseases are sometimes observed, but also in the manner of their diffusion. It is a 

 matter of common experience that removal from a locality in which cholera exists is 

 a remedy against the spreading of the disease, and the Grovernment of this country 

 has, for many years past, acted on this knowledge with regard to its troops and prisoners 

 with the greatest benefit. It is equally a matter of experience to find the population 

 of one part of a district suffering severely from fever, whereas others are practically 

 exempt, without any very evident difference in the localities being observable ; and just 

 as in the case of an outbreak of cholera, how often has it not been observed that crossing 

 to the other side of a river or shifting a ship a few hundred yards from where it had 

 been at anchor, has sufficed to put an end to a regular epidemic of malarious affections ? 

 With regard to both affections tracts of country which suffer in one season are exempted 

 in the next, whilst districts formerly exempted are in their turn attacked : at the same 

 time, the two diseases manifest a decided predilection to attack some localities at all 

 seasons. 



It is not uncommon to find that cholera is described as passing over large tracts 

 of country, either with the wind or in its teeth, according to the particular views 

 entertained by the writer, leaving the impression on the mind of the reader that 

 some pernicious influence had passed over the land. But is it not a fact that cholera, 

 instead of spreading itself over the country on any systematic, geographical plan, often 

 appears simultaneously in districts perhaps a thousand miles apart? Does it not seem 

 more reasonable to infer that the disease was generated at or near the place of its 

 ' occurrence in the same manner as outbursts of malarious fevers ? 



There is nothing more remarkable in the production of an attack of cholera than 

 in the production of an attack of ague ; in some respects, indeed, the latter is the 

 more remarkable of the two, seeing that once acquired the symptoms may recur 



* " No chemist has yet beeu able to demonstrate the existence of malaria. We assume its existence from 

 certain observed efEects on the organism just as we do in the case of other poisons which produce certain specific 

 diseases. Malaria is believed to be the product of organic decomposition in soils, whatever may be their mineral 

 composition ; water is indispensable to the process, and a high temperature, although not absolutely necessary? 

 greatly aids it. . . . It is often found in sandy soils and arid-looking plains, devoid of vegetation ; but in all 

 such cases the soil will be found to contain a considerable portion of organic matter, and water will be found not 

 far from the surface, either in the shape of subterraneous streams, or detained by a bed of clay below the sand. 

 . . . Malaria is also generated in hard rocks such as granite and trap, in a disintegrating state. A notable 

 example is the island of Hongkong, which consists entirely of weathered and decaying granite." — W. C. Maclean 

 on " Malarial Fevei's" in Reynolds' Syxtem of ]Ue<Iiomc,<2nd Edit., Vol. I., p. 591. 



