Tegetmeier 'Poultry Book' 1866 page 102.), though so fine and vigorous in England, suffers more from frost than any other breed. The Arrindy silk moth introduced from Bengal, and the Ailanthus moth from the temperate province of Shan Tung, in China, belong to the same species, as we may infer from their identity in the caterpillar, cocoon, and mature states (24/48. Dr. R. Paterson in a paper communicated to Bot. Soc. of Canada quoted in the 'Reader' 1863 November 13.); yet they differ much in constitution: the Indian form "will flourish only in warm latitudes," the other is quite hardy and withstands cold and rain.
[Plants are more strictly adapted to climate than are animals. The latter when domesticated withstand such great diversities of climate, that we find nearly the same species in tropical and temperate countries; whilst the cultivated plants are widely dissimilar. Hence a larger field is open for inquiry in regard to the acclimatisation of plants than of animals. It is no exaggeration to say that with almost every plant which has long been cultivated, varieties exist which are endowed with constitutions fitted for very different climates; I will select only a few of the more striking cases, as it would be tedious to give all. In North America numerous fruit-trees have been raised, and in horticultural publications,--for instance, in that by Downing,--lists are given of the varieties which are best able to withstand the severe climate of the northern States and Canada. Many American varieties of the pear, plum, and peach are excellent in their own country, but until recently, hardly one was known that succeeded in England; and with apples (24/49. See remarks by Editor in 'Gardener's Chronicle' 1848 page 5.), not one succeeds. Though the American varieties can withstand a severer winter than ours, the summer here is not hot enough. Fruit-trees have also originated in Europe with different constitutions, but they are not much noticed, because nurserymen here do not supply wide areas. The Forelle pear flowers early, and when the flowers have just set, and this is the critical period, they have been observed, both in France and England, to withstand with complete impunity a frost of 18 deg and even 14 deg Fahr., which killed the flowers, whether fully expanded or in bud, of all other kinds of pears. (24/50. 'Gardener's Chronicle' 1860 page 938. Remarks by Editor and quotation from Decaisne.) This power in the flower of resisting cold and afterwards producing fruit does not invariably depend, as we know on good authority (24/51. J. de Jonghe of Brussels in 'Gardener's Chronicle' 1857 page 612.), on general constitutional vigour. In proceeding northward, the number of varieties which are found capable of resisting the climate rapidly decreases, as may be seen in the list of the varieties of the cherry, apple, and pear, which can be cultivated in the neighbourhood of Stockholm. (24/52. Ch. Martius 'Voyage Bot. Cotes Sept. de la Norvege' page 26.) Near Moscow, Prince Troubetzkoy planted for experiment in the open ground several varieties of the pear, but one alone, the Poire sans Pepins, withstood the cold of winter. (24/53. 'Journal de l'Acad. Hort. de Gand' quoted in 'Gardener's Chronicle' 1859 page 7.) We thus see that our fruit-trees, like distinct species of the same genus, certainly differ from each other in their constitutional adaptation to different climates.
With the varieties of many plants, the adaptation to climate is often very close. Thus it has been proved by repeated trials "that few if any of the English varieties of wheat are adapted for cultivation in Scotland" (24/54. 'Gardener's Chronicle' 1851 page 396.); but the failure in this case is at first only in the quantity, though ultimately in the quality, of the grain produced. The Rev. M.J. Berkeley sowed wheat-seed from India, and got "the most meagre ears," on land which would certainly have yielded a good crop from English wheat. (24/55. Ibid 1862 page 235.) In these cases varieties have been carried from a warmer to a cooler climate; in the reverse case, as "when wheat was imported directly from France into the West Indian Islands, it produced either wholly barren spikes or furnished with only two or three miserable seeds, while West Indian seed by its side yielded an enormous harvest." (24/56.