THE PARALLEL GROWTH OF OPPOSITES 27 



ncreased general adaptation to the surroundings has not 

 been one of them. The giant strawberry, the pouter or 

 fantail pigeon, the racehorse, the improved bullock, are not 

 inferior in complexity to their wild congeners, but, instead 

 of gaining or even remaining stationary in this respect, have 

 lost the faculty of self-preservation, which is the distinguish 

 ing-mark of wild species ; and, as soon as the breeder s 

 protection is withdrawn, will either revert to something 

 like their original form, or disappear in the struggle for 

 existence. The wild forms, where they exist, are already so 

 far adapted to their environment as to be able to persist 

 while that remains unchanged, and artificial variations are 

 nearly certain to disturb the balance on which their security 

 depends. This principle is so well illustrated in a paper in 

 the Times of September 9, 1899, that I need no apology for 

 quoting the whole passage : 



( There are two ways in which science and invention can 

 produce, and have produced, a large increase in the yield 

 of sugar from the raw material, whether cane or beet. One 

 is by inducing a larger initial richness in the sugar-producing 

 juice, by means of experimental cultivation, and judicious 

 selection of the plant which yields it. ... The saccharine 

 matter in any plant is, under natural conditions, a deter 

 minate and probably a constant factor in the physiological 

 economy of the plant. Left to nature and itself, the plant 

 will only produce just so much sugar as is conducive to its 

 physiological well-being, and no more. But, just as we can 

 by breeding and feeding induce in our domestic animals 

 qualities neither native to the animal nor conducive to its 

 physiological welfare, but specially adapted to the several 

 uses we require the different animals to subserve, so, by a 

 similar method of cultivation and selection, we can develop 

 in plants, far beyond their physical needs, the particular 

 qualities and capacities which best subserve our own purposes 

 and requirements. 



In Germany, the yield of sugar in beetroot, owing to 



the invaluable assistance which German chemists have given 



to the agriculturists, rose, during the period between 



1840 and 1899 from 5 72 to 13 per cent. 1 If the improved 



1 Contemporary Review, May, 1904. 



