272 FOOTNOTES FROM 



these vegetable epidemics, and leaves us even in the 

 worst seasons a reasonable supply of the first necessary 

 of life, thus presenting a sublime fact upon which faith, 

 which is better than independence, can rest in peace ! 



The failure of the potato crop, which several years ago 

 came like one of those sudden and unexpected hurricanes 

 of the tropics, carrying death and desolation in their 

 train, is doubtless vivid in the recollection of all. This 

 root, from its extraordinary productiveness, with little 

 labour or exertion of any kind, became gradually a sub- 

 stitute in whole districts, especially in Ireland and the 

 Highlands of Scotland, for the older cereal crops, as the 

 staple food of the people ; so that when a blight fell 

 upon it, and the crop everywhere completely failed, hun- 

 dreds of thousands were deprived of their sole means of 

 subsistence, famine and its consequeut malignant fevers 

 rapidly spread throughout the land, and the social and 

 agricultural system based upon this uncertain and narrow 

 foundation was convulsed and completely broken up. 

 Various attempts have been made to account for this 

 melancholy failure. Some have attributed it to the at- 

 tacks of the Aphis rapce, a most rapacious and prolific 

 insect ; others to unfavourable atmospheric conditions ; 

 and a third class to the growth of minute parasitic fungi 

 or mould. The truth in all likelihood lies in a combina- 

 tion of the two last opinions ; the one being the predis- 

 posing cause, and the other the consequent effect. A 

 minute fungus, called Botrytis infestans (Fig. 39), con- 

 sisting of grey interwoven filaments, bearing a jointed 

 stalk which branches at the top, each division carrying 

 a rounded spore, appears to be almost invariably con- 



