88 DARWINISM chap. 



cracks and falls to pieces, just as occurs in a wild gourd 

 (C. momordica).^ 



Variations of Flowers. 



Turning to flowers, we find that in the same genus as our 

 currant and gooseberry, which we have cultivated for their 

 fruits, there are some ornamental species, as the Ribes sanguinea, 

 and in these the flowers have been selected so as to produce deep 

 red, pink, or white varieties. When any particular flov^er be- 

 comes fashionable and is grown in large quantities, variations 

 are always met with sufficient to produce great varieties of tint 

 or marking, as shown by our roses, auriculas, and geraniums. 

 When varied leaves are required, it is found that a number of 

 plants vary sufficiently in this direction also, and we have 

 zonal geraniums, variegated ivies, gold and silver marked 

 hollies, and many others. 



Variations of Domestic Animal-; 



Coming now to our domesticated animals, we find still more 

 extraordinary cases ; and it appears as if any special quality or 

 modification in an animal can be obtained if we only breed it 

 in sufficient quantity, watch carefully for the required varia- 

 tions, and carry on selection with patience and skill for a 

 sufficiently long period. Thus, in sheep we have enormously 

 increased the wool, and have obtained the power of rapidly 

 forming flesh and fat ; in cows we have increased the produc- 

 tion of milk ; in horses we have obtained strength, endurance, 

 or speed, and have greatly modified size, form, and colour ; in 

 poultry we have secured various colours of i)lumage, increase 

 of size, and almost perpetual egg-laying. But it is in dogs and 

 pigeons that the most marvellous changes have been eff'ected, 

 and these require our special attention. 



Our various domestic dogs are believed to have originated 

 from several distinct wild species, because in every part of 

 the world the native dogs resemble some wild dogs or wolves 

 of the same country. Thus perhaps several species of wolves 

 and jackals were domesticated in Aery early times, and from 

 breeds derived from these, crossed and improved by selection, 



^ These facts are taken from Darwin's Domesticated A nimals avd Cultivated 

 Plants, vol. i. pp. 359, 360, 392-401 ; vol. ii. pp. 231, 275, 330. 



