CARE REQUIRED IN SELECTION. 1 55 



of animals and plants. To practised gardeners and farmers, 

 you may give distinct commissions, and say, for example, 

 I wish to have this species of plant with this or that colour, 

 and with this or that shape. Where breeding has reached 

 the perfection which it has attained in England, gardeners 

 and farmers are frequently able to furnish to order the 

 desired result within a definite period, that is, at the end of 

 a number of generations. Sir John. Sebright, one of the most 

 experienced English pigeon-breeders, could assert that in 

 three years he would produce any form of feather, but that 

 he required six years to obtain any desired form of the head 

 and beak. In the process of breeding the merino-sheep of 

 Saxony, the animals are three times placed on a table beside 

 one another, and most carefully compared and studied. 

 Each time only the best sheep with the finest wool are 

 selected, so that in the end, out of a great multitude, there 

 remain only some few animals, but their wool is exquisitely 

 fine, and only these last are used in breeding. We see, 

 therefore, that the causes through which, in artificial 

 breeding, great eflfects are produced, are unusually simple, 

 and these great efiects are obtained simply by accumulating 

 the diflferences which in themselves are very insignificant, 

 and become surprisingly increased by a continually repeated 

 selection. 



Before we pass on to a comparison of this artificial with 

 natural breeding, let us see what natural quahties of the 

 organisms are made use of by the artificial breeder or 

 cultivator. We can trace all the different qualities which 

 here come into play to physiological fundamental qualities of 

 the organism, which are common to all animals and plants^ 

 and are most closely connected with the functions of 



