24:8 CAUSES OF VAE I ABILITY. Chap. XXII 



from the great number of seedlings which spring up there in the 

 woods. I infer that this is the case from a remark made by a 

 French gardener, 18 who regards it as a national calamity that such 

 a number of pear-trees are periodically cnt down for firewood, before 

 they have borne fruit. The new varieties which thus spring up in 

 the woods, though they cannot have received any excess of nutri- 

 ment, will have been exposed to abruptly changed conditions, but 

 whether this is the cause of their production is very doubtful. 

 These varieties, however, are probably all descended 19 from old 

 cultivated kinds growing in adjoining orchards — a circumstance 

 which will account for their variability ; and out of a vast number 

 of varying trees there will always be a good chance of the appear- 

 auce of a valuable kind. In North America, where fruit-trees 

 frequently spring up in waste places, the Washington pear was 

 found in a hedge, and the Emperor peach in a wood. 2 " 



With respect to wheat, some writers have spoken- 1 as if it were 

 an ordinary event for new varieties to be found in waste places ; the 

 Fenton wheat was certainly discovered growing on a pile of basaltic 

 detritus in a quarry, but in such a situation the plant would 

 probably receive a sufficient amount of nutriment. The Chidham 

 wheat was raised from an ear found on a hedge : and Hunters 

 wheat was discovered by the roadside in Scotland, but it is not said 

 that this latter variety grew where it was found.' 22 



Whether our domestic productions would ever become so 

 completely habituated to the conditions under which they 

 now 1 vi'. as to cease varying, we have no sufficient means for 

 judging. But, in fact, our domestic productions are never 

 exposed for a great length of time to uniform conditions, and 

 it is certain that our most anciently cultivated plants, as well 

 as animals, still go on varying, for all have recently under- 

 gone marked improvement. In some few cases, however, 

 plants have become habituated to new conditions. Thus, 

 Metzger, who cultivated in Germany during many years 

 numerous varieties of wheat, brought from different coun- 

 tries.- 3 states that some kinds were at first extremely vari- 

 able, but gradually, in one instance after an interval of 



18 Duval, 'Hist, du Poirier,' 1849, aboriginal species. 



j.. j. 20 Downing. -Fruit-trees of North 



19 I infer that this is the fact from America,' p. 422 ; Foley, in ' Transact. 

 lions' statement (' Arbres Frui- Hort. Soc.,' vol. vi. p. 412. 



tiers,' 1835, torn. i. p. 446) that he il ' Gard. Chronicle,' 1847, p. 244. 



:n the woods seedlings resembling 22 'Gardener's Chronicle,' 1841, p. 



all the chief cultivated races of both 38 j 18' , p. 700 ; 1854. p. 650. 



the pear and apple. Van Mons, how- " ' Die Getreidearten,' 1843, s. fry 



ivei looked at these wild varieties as 116, 117. 



