S58 PEINCIPLES OF GARDENING. [CH. VIII. 



that have remained in the ground until completely 

 perfected ; and I believe, under ordinaiy treatment, 

 this to be the fact, for it is rational. The process 

 of ripening proceeds in the potato, as in the apple, 

 after it has been gathered, and until that is per- 

 fected, it is accumulating vigour, shews no appetency 

 to vegetate, consequently is not exhausting its 

 vitality, which is a great point, considering the 

 careless mode usually adopted to store them through 

 the winter ; for this energy commences its decHne 

 from the moment it begins to develope the parts of 

 the future plant. Tubers taken from the soil before 

 perfectly ripe, never are so early in shewing sjinp- 

 toms of vegetation. Crichton, Hunter, and Young, 

 in some of the works before referred to, have also 

 agreed, that exposing the sets to light and air, 

 allomng them to become diy and shrivelled, also 

 induces the curl in the plants arising from them. 

 This result of experience also confirms my con- 

 clusion, that the disease aiises from deficient vital 

 energ}^; for no process more than this drying one of 

 exposui'e to the light and air, tends to take away from 

 a tuber the power of vegetating altogether. A farmer, 

 Mr. G. Allaker, residing in the same village that I 

 did, employed in the year 1836 rather small sets : 

 cutting a moderate-sized potato into at least two 

 pieces. Unfavourable weather, other business, and 

 a somewhat dilatory habit, caused him to leave those 



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