288 Epidemics. 



animal spore or fungoid diffusible germs, which as a perma- 

 nent growth is highly improbable. 



Even here we are met by the fact of such a disease 

 as cholera, being an old and endemic form of disease, 

 changing its character, and spreading more than the locust 

 in every clime under the sun. How an eruption from the 

 same centre, if such had been the case, could give new 

 powers of diffusion and extension, centuries after, is as 

 utterly inconceivable as that an eruption should have first 

 originated in one part of the globe, and yet eruptions of 

 apparently a like nature or character should have never 

 had a similar effect in any other part of the globe. 



Again, heat, either in excess or in defect, is a great factor 

 of disease. The extremes between 32 and 120 Fahr. 

 seem to be moderately well borne by vegetable life, and if 

 we consider the teeming multitudes in India, China, and 

 Central Africa, and of Central and South Europe, it appears 

 to be equally well borne in animal life as represented in 

 man, who, it must be observed, is a nude or clothed animal 

 according to the exigencies of climate and customs, etc. 

 But thirty degrees, above or below these points or ranges, 

 is fraught with the most dangerous consequences to both 

 animal and vegetable life; yet epidemic disease never ap- 

 pears to avail itself of these extremes for the end of encom- 

 passing with disease and death the multitude of victims 

 which fall under its fatal grasp. 



But it must be observed that during epidemic eras slow 

 and gradual changes in the earth's temperature have taken 

 place but very much quicker, and of a far more marked 

 character than ever could have been brought about within 

 the historic age of man by a slow decrease in the eccen- 

 tricity of the earth's orbit, as maintained by the late Sir J. 

 Herschel ; which changes, from their speed, indicate some- 

 thing within the earth itself of a slow and gradual nature, 



