CHAP. XVIII. FROM CHANGED CONDITIONS. 129 



that he. has himself witnessed decided advantage from obtaining 

 bulbs of the onion, tubers of the potato, and various 6eeds, all of 

 the same kind, from different soils and distant parts of England. 

 He further states that with plants propagated by cuttin.es, as with 

 the Pelargonium, and especially the Dahlia, manifest advantage is 

 derived from getting plants of the same variety, which have been 

 cultivated in another place ; or, " where the extent of the place 

 " allows, to take cuttings from one description of soil to plant on 

 " another, so as to afford the change that seems so necessary to the 

 " well-being of the plants." He maintains that after a time an 

 exchange of this nature is " forced on the grower, whether he be 

 " prepared for it or not." Similar remarks have been made by 

 another excellent gardener, Mr. Fish, namely, that cuttings of the 

 same variety of Calceolaria, which he obtained from a neighbour, 

 " showed much greater vigour than some of his own that were 

 " treated in exactly the same manner," and he attributed this 

 solely to his own plants having become " to a certain extent worn 

 " out or tired of their quarters." Something of this kind appar- 

 ently occurs in grafting and budding fruit-trees ; for, according to 

 Mr. Abbey, grafts or buds generally take with greater facility on 

 a distinct variety or even species, or on a stock previously grafted, 

 than on stocks raised from seeds of the variety which is to be 

 grafted ; and he believes this cannot be altogether explained by 

 the stocks in question being better adapted to the soil and climate 

 of the place. It should, however, be added, that varieties grafted 

 or budded on very distinct kinds, though they may take more 

 readily and grow at first more vigorously than when grafted on 

 closely allied stocks, afterwards often become unhealthy. 



I have studied M. Tessier's careful and elaborate experiments, 6 

 made to disprove the common belief that good is derived from a 

 change of seed ; and he certainly shows that the same seed may 

 with care be cultivated on the same farm (it is not stated whether 

 on exactly the same soil) for ten consecutive years without loss. 

 Another excellent observer, Colonel Le Couteur, 7 has come to the 

 same conclusion ; but then he expressly adds, if the same seed be 

 used, " that which is grown on land manured from the mixen one 

 " year becomes seed for land prepared with lime, and that again 

 " becomes seed for land dressed with ashes, then for land dressed 

 " with mixrd manure, and so on." But this in effect is a systematic 

 exchange of seed, within the limits of the same farm. 



On the whole the belief, which has long been held by many 

 cultivators, that good follows from exchanging seed, tubers, 

 &c, seems to be fairly well founded. It seems hardly credible 

 that the advantage thus derived can be due to the seeds, 

 especially if very small ones, obtaining in one soil some 



,; •Mem. de I' Acad, des Science*,' 7 'On the Varieties of Wheat,' }>• 



1790, p. 209. 52. 



VOL. II. E 



