Chap. XXIV. ACCLIMATISATION. 305 



instance of a plant which has not become hardier since its 

 first introduction into Britain. We hear, however, on excel- 

 lent authority, 80 that some very fine seed, imported from abroad, 

 produced plants " which blossomed most profusely, but were 

 " nearly all but abortive, whilst plants grown alongside from 

 " English seed podded abundantly ; " and this apparently 

 shows some degree of acclimatisation in our English plants. 

 We have also seen that seedlings of the kidney -bean occasion- 

 ally appear with a marked power of resisting frost ; but no 

 one, as far as I can hear, has ever separated such hardy 

 seedlings, so as to prevent accidental crossing,, and then 

 gathered their seed, and repeated the process year after year. 

 It may, however, be objected with truth that natural selection 

 ought to have had a decided effect on the hardiness of our 

 kidney-beans ; for the tenderest individuals must have been 

 killed during every severe spring, and the hardier preserved. 

 But it should be borne in mind that the result of increased 

 hardiness would simply be that gardeners, who are always 

 anxious for as early a crop as possible, would sow their seed 

 a few days earlier than formerly. Kow, as the period of sowing 

 depends much on the soil and elevation of each district, and 

 varies with the season; and as new varieties have often been 

 imported from abroad, can we feel sure that our kidney-beans 

 are not somewhat hardier ? I have not been able, by searching 

 old horticultural works, to answer this question satisfactorily. 

 On the whole the facts now given show that, though habit 

 does something towards acclimatisation, yet that the ap- 

 pearance of constitutionally different individuals is a far more 

 effective agent. As no single instance has been recorded 

 either with animals or plants of hardier individuals having 

 been long and steadily selected, though such selection is 

 admitted to be indispensable for the improvement of any other 

 character, it is not surprising that man has done little in the 

 acclimatisation of domesticated animals and cultivated plants. 

 We need not, however, doubt that under nature new races 

 and new species would become adapted to widely different 

 climates, by variation, aided by habit, and regulated by 

 natural selection. 



80 Messrs. Hardy and Son, in 'Gard. Chronicle,' 1856, p. £89. 



