iv VARIATION UXDER DOMESTICATION 95 



that killed the flowers and buds of all other kinds of pears. 

 Wheat, which is grown over so large a portion of the world, has 

 become adapted to special climates. Wheat imported from 

 India and sown in good wheat soil in England produced the 

 most meagre ears ; while wheat taken from France to the 

 West Indian Islands produced either wholly barren spikes or 

 spikes furnished with two or three miserable seeds, while 

 West Indian seed by its side yielded an enormous harvest. The 

 orange was very tender when first introduced into Italy, and 

 continued so as long as it was propagated by grafts, but 

 when trees were raised from seed many of these were found 

 to be hardier, and the orange is now perfectly acclimatised in 

 Italy. Sweet-peas (Lathyrus odoratus) imported from England 

 to the Calcutta Botanic Gardens produced few blossoms and 

 no seed ; those from France flowered a little better, but still 

 produced no seed, but plants raised from seed brought from 

 Darjeeling in the Himalayas, but originally derived from 

 England, flower and seed profusely in Calcutta. 1 



An observation by Mr. Darwin himself is perhaps even 

 more instructive. He says: "On 24th May 1864 there 

 was a severe frost in Kent, and two rows of scarlet runners 

 (Phaseolus multiflorus) in my garden, containing 390 plants of 

 the same age and equally exposed, were all blackened and 

 killed except about a dozen plants. In an adjoining row of 

 Fulmer's dwarf bean (Phaseolus vulgaris) one single plant 

 escaped. A still more severe frost occurred four days after- 

 wards, and of the dozen plants which had previously escaped 

 only three survived ; these were not taller or more vigorous 

 than the other young plants, but they escaped completely, 

 with not even the tips of their leaves browned. It was im- 

 possible to behold these three plants, with their blackened, 

 withered, and dead brethren all around them, and not see at 

 a glance that they differed widely in their constitutional power 

 of resisting frost." 



The preceding sketch of the variation that occurs among 

 domestic animals and cultivated plants shows how wide it is 

 in range and how great in amount ; and we have good reason 

 to believe that similar variation extends to all organised beings. 

 In the class of fishes, for example, we have one kind which has 

 1 Animals and Plants under Domestication, vol. ii. pp. 307-311. 



