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in several instances, tried to renovate the vigor of old and excellent,, 

 ^nearly expended varieties, by change of soil and mode of culture; but I 

 never, in any degree, succeeded, all become unproductive and worthless." 

 ■Dr. Lindley, also, in speaking of thepotatoe, says, "it is certain that the 

 productive power of a given variety of the potatoe,^is in proportion to 

 its youth, and that all varieties cease, after a few years, to be as produc- 

 tive as they once were. When Mr. Knight's seedlings Avere originally 

 , tried, they yielded, in one case, at the rate of sixty-eight and seventy 

 for one; no such crops can now be obtained from them." This hypoth- 

 esis, till within the last few years, made but little progress, and, I believe, 

 -it is owing to the want of a knowledge of, or faith in, the truth of this 

 law, and to the consequent neglect of frequently renewing the vigor of 

 .the potatoe, by raising a succession of seedling plants, from seeds saved 

 ihom vigorous and healthy varieties, that the degeneracy of the potatoe 

 'considered in the mass, or as a species, is chiefly due. 



All other agricultural plants have progressively improved, the potatoe 

 alone has progressively deteriorated. The former are propagated exclu- 

 sively by seeds, the latter chiefly by divisions of the tuber ; and this difler- 

 €nce in the mode of propagation furnishes a key to the true explanation of 

 the cause of the bad health of the potatoe, as compared with other crops. 

 There is no other instance of an entire species of plant having degener- 

 ated like the potatoe. The varieties of the ranunculus and anemone, 

 which are propagated by their tubers, are equally short-lived plants, but 

 great attention has been paid to raising new varieties from seeds. To 

 raise new sorts of these flowers is a most bewitching, and, moreover, a 

 profitable pursuit, and florists know Avell, that in order to reach nearer to 

 perfection, they must start from the most perfect flowers they most recent- 

 ly obtained. But there have been no inducements for continued efi"orts 

 to improve the potatoe, by raising new varieties from seeds year after 

 year. Other plants had far higher attractions for those who followed 

 the pursuit as an amusement: and as a commercial speculation, there 

 was little prospect, indeed, of its paying ; hence, we have been trying 

 over and over again, with a marvellous perversity, to make individual 

 plants live for ever, which nature intended should only live for a time, 

 and then from parents feeble or old, we have vainly expected ofi'spring 

 hardy and strong ; herein we have violated the laws of nature ; by these 

 practices we have gradually reduced the constitution of successive gener- 

 ations of the potatoe ; and we have consequently gradually increased th« 



