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some tubers. It may be thought this is an inquiry into the operation 

 of immediate causes, which, although very curious, is of no practical 

 importance, but this is an error : it is a question of vast amount. If 

 this disease is really produced by germs of endophytal fungi, nestling 

 within the structure of the parent ; many of these germs will remain 

 in a latent condition within the cellular structure of the potato, and 

 when such an apparently sound but really infected tuber is used for 

 planting in the ensuing year, they will be called into activity again 

 during the process of germination of the potato-set, and the same 

 disease will probably appear in the potato crop next autumn ; whereas, 

 if the present murrain be only the effect of an unusually cold and wet 

 season, it may reasonably be hoped a more congenial summer will rid 

 us of the calamity. At all events, it will be highly desirable that in 

 the next planting-season the farmer should select his sets, not only 

 from sound tubers, but if possible from seed plants obtained from lo- 

 calities in which the disease did not appear. 



I do not venture to speak dogmatically on the exciting cause of the 

 murrain, especially when so many excellent observers maintain a con- 

 trary opinion, but I am not perfectly satisfied these fungi are really 

 more than accidental accompaniments, rather than the essence, as it 

 were, of the malady. I cannot divest my mind of the impression, 

 that with more probability it may be referred to atmospheric influ- 

 ences, that is, to the direct debilitating operation of a prolonged low 

 temperature, combined with excessive moisture, upon the structure of 

 the plant. The potato plants, as I have before observed, exhibited 

 an unusual rankness of growth during the summer, when their struc- 

 tures, doubtless, were over-filled with watery sap, just that state of the 

 vegetable constitution which renders their vitality low, and therefore 

 less able to resist the debilitating effects of cold. They therefore 

 in many situations perished by what I shall denominate vegetable 

 sphacelus. Without speaking confidently, I merely state I am at 

 present rather inclined to take this view of the subject, which is 

 borne out by many analogies in the animal economy. It is a singular 

 fact, if true, that where the potato crop is exposed to the stimulating 

 atmosphere of the sea, e. g. the coast of Devon and Somerset, the 

 murrain is said not to have appeared. Perhaps the sea-breeze, loaded 

 with salt impregnation, may operate as a tonic or stimulant to the 

 foliage of the potato-plants, and thus preserve them from the ten- 

 dency to decay. The whole of Europe in which the potato-murrain 

 rages, has suffered fi-om the same ungenial wet and cold summer 

 which has afflicted England ; therefore the same explanation may be 



