140 THE HISTOKY OF CEEATION. 



and varieties), is of the utmost importance to the theory of 

 selection. What is most surprising in such a comparison is 

 the remarkably short time in which man can produce a 

 new form, and the high degree in which this form, pro- 

 duced by man, can deviate from the original form. While 

 wild animals and plants, one year after another, appear 

 to the zoologist and botanist approximately in the same 

 form, so as to have given rise to the false doctrine of the 

 constancy of species, domestic animals and garden plants, 

 on the other hand, display the greatest changes within a 

 few years. The perfection which gardeners and farmers 

 have attained in the art of selection now enables them, in 

 the space of a few years, arbitrarily to create entirely new 

 animal and vegetable forms. For this purpose it is only 

 necessary to keep and propagate the organism under the 

 influence of special conditions — which are capable of pro- 

 ducinof new formations —and even at the end of a few 

 generations new species may be obtained, which difier from 

 the original form in a much higher degree than so-called 

 good species in a wild state difier from one another. This 

 fact is extremely important, and we cannot lay sufficient 

 stress upon it. The assertion is not true that cultivated 

 forms descended from one and the same primary form do 

 not difier from one another as much as wild animal and 

 vegetable species difier among themselves. If we only make 

 comparisons, without prejudice, we can very easily perceive 

 that a number of races or varieties which have been derived 

 from a single cultivated form, within a short series of yeai-s, 

 differ from one another in a higher degree than so-called 

 good species (bonse species), or even different genera of one 

 family, in the wild state. 



