52 RELATION OF DISEASE TO SOILS AND MANURES. 



unknown agent. The cause of the potatoe disease does 

 not appear at all analogous to any agent of this kind. 



(203.) Upon the whole it is probable that certain ab- 

 normal qualities of the atmosphere have influenced to a 

 very slight extent the present universal epidemic. 



CHAPTER VIII. 



RELATION OF DISEASE TO SOILS AND MANURES. 



Soil which suits the potatoe (205). Diseased in all soils (206). 

 Statement of Mr. Latham (207) ; of Mr. Greatrex (209). Influ- 

 ence of wet soils on the disease (211). Guano and Animal Salts 

 (214). Influence of manures on the disease (216). 



(204.) EVERY plant requires a peculiar soil in which to 

 vegetate ; thus, ferns like a peaty soil, wheat a rich loamy 

 soil ; other plants thrive only in a sandy soil, and 'in fact 

 every plant has a peculiar soil in which it grows best. 



(205.) The potatoe plant succeeds best in a rich allu- 

 vial soil ; and in Yorkshire, where potatoes are grown for 

 the London market, it is a common practice to allow water 

 to deposit a sediment over land, till two or three feet of 

 rich mould are deposited. 



(206.) It might be thought that a wrong soil has caused 

 this epidemic, but the disease is to be found in every kind 

 of earth whatever. It is found round London in the light 

 alluvial soils left by the rivers Thames and Lea ; and it is 

 found in the stiff London clay, and in light gravel. 



