Now, if seedlings are raised from the May-leafing Lalande variety, grafted on another May-leafing variety, though both stock and graft have the same early habit of leafing, yet the seedlings leaf at various times, even as late as the 5th of June. (22/16. M. Cardan in 'Comptes Rendus' December 1848 quoted in 'Gardener's Chronicle' 1849 page 101.) Such facts as these are well fitted to show on what obscure and slight causes variability depends.
[I may here just allude to the appearance of new and valuable varieties of fruit-trees and of wheat in woods and waste places, which at first sight seems a most anomalous circumstance. In France a considerable number of the best pears have been discovered in woods; and this has occurred so frequently, that Poiteau asserts that "improved varieties of our cultivated fruits rarely originate with nurserymen." (22/17. M. Alexis Jordan mentions four excellent pears found in woods in France, and alludes to others ('Mem. Acad. de Lyon' tome 2 1852 page 159). Poiteau's remark is quoted in 'Gardener's Mag.' volume 4 1828 page 385. See 'Gardener's Chronicle' 1862 page 335, for another case of a new variety of the pear found in a hedge in France. Also for another case, see Loudon's 'Encyclop. of Gardening' page 901. Mr. Rivers has given me similar information.) In England, on the other hand, no instance of a good pear having been found wild has been recorded; and Mr. Rivers informs me that he knows of only one instance with apples, namely, the Bess Poole, which was discovered in a wood in Nottinghamshire. This difference between the two countries may be in part accounted for by the more favourable climate of France, but chiefly 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 (22/18. Duval 'Hist. du Poirier' 1849 page 2.), who regards it as a national calamity that such a number of pear-trees are periodically cut 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 nutriment, 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 (22/19. I infer that this is the fact from Van Mons' statement ('Arbres Fruitiers' 1835 tome 1 page 446) that he finds in the woods seedlings resembling all the chief cultivated races of both the pear and apple. Van Mons, however, looked at these wild varieties as aboriginal species.) 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 appearance 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. (22/20. Downing 'Fruit-trees of North America' page 422; Foley in 'Transact. Hort. Soc.' volume 6 page 412.)
With respect to wheat, some writers have spoken (22/21. 'Gardener's Chronicle' 1847 page 244.) 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 Hunter's wheat was discovered BY the roadside in Scotland, but it is not said that this latter variety grew where it was found. (22/22. 'Gardener's Chronicle' 1841 page 383; 1850 page 700; 1854 page 650.)]
Whether our domestic productions would ever become so completely habituated to the conditions under which they now live, 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 undergone marked improvement.