1110. Acclimatising seems to be most easily effected, in going from a hot to a cold climate, on herbaceous plants ; because it often happens that the frosts of winter are accompanied by snow, which shelters the plant from the inelemency of the atmosphere till the return of spring. Trees and shrubs, on the contrary, are acclimatised with more difficulty, because they cannot be so easily sheltered from the cold, owing to the greater length of their stems and branches. The acclimatising or naturalisation of vegetables is to be attempted by two modes : by sowing the seeds of successive generations, and by the difference of temperature produced by different aspects. Experience, however, has proved, that very little change takes place in the constitutions of plants, by either of these modes of treatment. An individual plant may be rendered more hardy, or more delicate, by local or other changes ; but the power of the species to resist cold or heat, drought or moisture, remains the same. Thus, the kidneybean, the nasturtium, the potato, and other plants from the southern hemisphere, though raised through numerous generations by seed in Britain, are as easily affected by the autumnal frosts as they probably were when first planted in our gardens.
