POPULAR SCIENCE. 7 



the philosopher it might be very interesting that the question 

 of spontaneous generation was settled in the negative that 

 the axiom omne ex ovo was upheld ; but what use, the utilita- 

 rian might still inquire, were all these proofs ? This we shall 

 presently see. Few of us who are old enough can have for- 

 gotten the discovery which the cholera visitation occasioned in 

 1849-50. Asiatic cholera was, comparatively speaking, a new 

 disease. Until this century had some way advanced, it had 

 never been seen or heard of even in India ; whence, having 

 gone forth, its origin was traced back to a localised region 

 corresponding with the delta of the Ganges ; and numerous 

 investigations, conducted by many persons working independ- 

 ently, associated it in some way with a detrimental crop of 

 rice. It was natural that microscopists should apply them- 

 selves to this rice. They did so ; and with the curious, 

 though not unexpected, result of actually discovering a mi- 

 nute fungus. Analogies came in aid. Rice is a grass, and 

 the fruit ordinarily called the seed of grasses was already 

 known as being prone to the growth of fungi. The so-called 

 smut of wheat is of this sort, as in like manner is rye ergot, 

 a material used as medicine by the physician. In this coun- 

 try a medical man, now deceased the late Dr. Snow first 

 called attention to the fact that the incidence of cholera was, 

 in every case known to him, traceable either to the eating or 

 drinking of things which in some way had been associated 

 with previous cholera patients, or else to the eating and 

 drinking of articles of food in which certain processes of de- 

 composition were going on. The late Mr. Warington of the 

 Apothecaries' Hall, though not a medical man, came to the 

 conclusion that Asiatic cholera depended in some way on the 

 incidence of a certain sort of fermentation ; which was equi- 

 valent to expressing the belief, in other words, that it de- 

 pended on the growth of microscopic fungi. 



Collateral evidence was soon forthcoming. The im- 

 munity of copper smelting-works from cholera had become 



