324 1 ON THE ct?RL IN POTATOES. 



Argument from means used, until they at last become what we wish. And 

 practice- " what may be deemed still a farther proof is, that those who 

 cultivate potatoes most successfully, in the low and early 

 parts of this country, where the disease chiefly exists, bring 

 a supply of seed-stock from the higher and later parts of 

 the country, for a change, every second year at farthest. 

 In such high places, from the lateness and wetness of the 

 climate, the farmers are prevented from planting their po- 

 tatoes so early as in the low country, and are also, from 

 the fear of early frosts, obliged to take up their crop 

 sooner ; consequently the tubers are never so highly ripened 

 as to weaken the vegetative principle in them. Here, then, 

 we have a strong practical testimony to the truth of the 

 docrine which has been advanced. 

 and the effects 0" 1 the other hand, in the early districts of the low 

 of its opposite, country, where, as has already been remarked, the disease 

 is principally known, particular kinds of potatoes are 

 planted year after year successively, from the same seed- 

 stock ; and most of the early kinds are planted soon in the 

 season, with a view to procure an early crop for the mar- 

 ket: a part of these is generally allowed to remain in the 

 ground till the usual time of taking up, to supply seed- 

 stock for the ensuing year: by this time, however, the 

 plants have become so ripe as to weaken very much the ve- 

 getative power of the tubers. This practice being repeated 

 for several years, at last so impairs the vegetative power in 

 the tubers, as to produce the curl; and there is no doubt, 

 that, if this practice were persevered in, it would ulti- 

 mately destroy the power of vegetation altogether, as I 

 have proved by experiments. 

 Potatoes to be There is yet another powerful cause, which weakens the 

 used for setting ve getative power in the tubers; and this is, the allowing 

 Ibe suffered to such plants as are intended to supply seed-stock for the en- 

 flower, suing year, to run to flower, and produce seed*. This 

 should in all cases be prevented, by cutting off the flowers 

 as they appear, even in embryo. Thus, by turning nature 

 from her ordinary course, we force her to exert herself in 



* It is generally the late sorts of potatoes, that produce seeds, 

 very few of the early kinds doing so. 



an other 



