Chap. XXIV. ACCLIMATISATION. 295 



one another in their manner of hunting, and in their ardour 

 after different kinds of game or vermin. 



With plants the period of vegetation is easily changed and 

 is inherited, as in the case of summer and winter wheat, 

 barley, and vetches ; but to this subject we shall immediatel}^ 

 return under acclimatisation. Annual plants sometimes 

 become perennial under a new climate, as I hear from Dr. 

 Hooker is the case with the stock and mignonette in Tasmania. 

 On the other hand, perennials sometimes become annuals, as 

 with the Ricinus in England, and as, according to Captain 

 Mangles, with many varieties of the heartsease. Von Berg ^° 

 raised from seed of Verhascum phoeniceum, which is usually a 

 biennial, both annual and perennial varieties. Some de- 

 ciduous bushes become evergreen in hot countries.^^ Eice 

 requires much water, but there is one variety in India which 

 can be grown without irrigation.*'^ Certain varieties of the 

 oat and of our other cereals are best fitted for certain soils. '^^ 

 Endless similar facts could be given in the animal and vege- 

 table kingdoms. They are noticed here because they illustrate 

 analogous differences in closely allied natural species, and 

 because such changed habits of life, whether due to habit, or 

 to the direct action of external conditions, or to so-called spon- 

 taneous variability, would be apt to lead to modifications of 

 structure. 



Acclimatisation. — From the previous remarks we are 

 naturally led to the much disputed subject of acclimatisation. 

 There are two distinct questions : Do A^arieties descended from 

 the same species differ in their power of living under different 

 climates ? And secondly, if they so differ, how have they 

 become thus adapted ? We have seen that Euroj)ean dogs do 

 not succeed well in India, and it is asserted,*'* that no one has 

 there succeeded in keeping the Newfoundland long alive ; but 

 then it may be argued, and probably Avith truth, that these 



•«o ' Flora,' 1835, B. ii. p. n04. *^ ' Gardeuer's Chronicle,' I80O, 



<» Alph. de CaadoUe, ' Geograph. pp. 204, 219. 



Bot.,' torn. ii. p. 1078. ** Rev. R. Everest, ' Journal As. 



*'^ Royle, 'Illustrations of the Soc. of Bengal,' vol. iii. p. 19. 

 Botany of the Himalaya,' p. 19. 



