128 ON THE GOOD DERIVED Chap. XYI1I. 



The belief that plants are thus benefited, whether or not well 

 founded, has been firmly maintained from the time of Columella, 

 who wrote shortly after the Christian era, to the present day ; and 

 it now prevails in England, France, and Germany. 1 A sagacious 

 observer, Bradley, writing in 1724, 2 says, " When we once become 

 " Masters of a good Sort of Seed, we should at least put it into 

 " Two or Three Hands, where the Soils and Situations are as dif- 

 " ferent as possible ; and every Year the Parties should change 

 " with one another ; by which Means, I find the Goodness of the 

 " Seed will be maintained for several Years. For Want of this 

 "Use many Farmers have failed in their Crops and been great 

 " Losers." He then gives his own practical experience on this 

 head. A modern writer s asserts, " Nothing can be more clearly 

 " established in agriculture than that the continual growth of any 

 " one variety in the same district makes it liable to deterioration 

 " either in quality or quantity." Another writer states that he 

 sowed close together in the same field two lots of wheat-seed, the 

 product of the same original stock, one of which had been grown 

 on the same land and the other at a distance, and the difference in 

 favour of the crop from the latter seed was remarkable. A gentle- 

 man in Surrey who has long made it his business to raise wheat to 

 sell for seed, and who has constantly realised in the market higher 

 prices than others, assures me that he finds it indispensable con- 

 tinually to change his seed ; and that for this purpose he keeps two 

 farms differing much in soil and elevation. 



With respect to the tubers of the potato, I find that at the present 

 day the practice of exchanging sets is almost everywhere followed. 

 The great growers of potatoes in Lancashire formerly used to get 

 tubers from Scotland, but they found that " a change from the 

 moss-lands, and vice versa, was generally sufficient." In former 

 times in France the crop of potatoes in the Yosges had become 

 reduced in the course of fifty or sixty years in the proportion from 

 120-150 to 30-40 bushels ; and the famous Oberlin attributed the 

 surprising good which he effected in large part to changing the sets. 4 



A well-known practical gardener, Mr. Eobson, 5 positively states 



1 For England, see below. For Rev. D. Walker's ' Prize Essay of 

 Germany. se^Metzger, 'Getreidearten,' Highland Agricult. Soc.,' vol. ii. p. 

 1341, s. 63. For France. Loiseleur- 200. Also Marshall's ' Minutes of 

 Deslonsrchamps ('Consid. sur les Agriculture,' November, 1775. 

 Cereales,' 1843, p. 200) gives nu- 4 Oberlin's ' Memoirs,' Eng. trans- 

 merous references on this subject. For lab., p. 73. For Lancashire, see 

 Southern France, see Godron, ' Florula Marshall's ' Review of Reports,' 1808, 

 Juvenalis,' 1854. p. 28. p. 295. 



2 'A General Treatise of Hus- 5 ' Cottage Gardener,' 1856, p. 186. 

 bandry,' vol. iii. p. 58. For Mr. Robson's subsequent state- 



3 'Gardener's Chronicle and Agri- ments, see ' Journal of Horticulture,' 

 cult. Gazette,' 1858, p. 247; and for Feb. 18, 1866, p. 121. For Mr. 

 the second statement, Ibid., 1850, p. Abbey's remarks on grafting, &c, 

 702. On this same subject, see also Ibid., July 18, 1865, p. 44. 



