238 THE NEW AGRICULTURE. 



was growing upon the prairies of the Dakotas ; how long 

 to have cross-fertilized the English walnut with the variety 

 which grows in a state of nature on the Pacific Slope? No 

 time could be set when these and similar phenomena would 

 be likely to happen, but man brought them about almost within 

 a twelve-month. 



While, therefore, Nature has the advantage of time in 

 bringing about the striking differences which we see about 

 us in the animal and in the vegetable world, we have 

 to remember that the purpose of her work and the 

 purpose of man's work are not identical ; that she has pro- 

 duced many changes which he will never want to produce ; 

 that she has been intent upon preserving many forms which 

 he will not care to preserve; that much of her work, as of 

 the production of climate and earth surface, he simply utilizes 

 as it is or modifies to suit his convenience; that his work is 

 incomparably more concentrated in scope, having to do only 

 with his own personal wellbeing and pleasure; and that he 

 works by methods infinitely more direct, precise and certain 

 than Nature usually employs for the purposes now under con- 

 sideration. 



We have seen that the most important principle which Na- 

 ture employs in the development of varieties and species is that 

 of selection. This also is man's chief resource. Fifty years 

 ago Darwin could write : "It is certain that several of our 

 eminent breeders have, even within a single lifetime, modi- 

 fied to a large extent some breeds of cattle and sheep. Breed- 

 ers habitually speak of an animal's organization as some- 

 thing quite plastic, which could be moulded almost as they 

 please. Youatt. who was probably better acquainted with the 

 work of agriculturists than almost any other individual, and 



