MAN'S CONQUEST OF NATURE 571 



sunlight, water, cultivation, or fertilizer. Along with this eame the 

 seizing upon favorable variations and their continuance by cultivation. 

 Lack of precise knowledge prevented certain success, and progress 

 was slow. Crop production, moreover, has always been, and will 

 continue to be, to a large degree deperdent upon the vagaries of the 

 weather, as the effects of the recent draughts in the United States 

 prove. Nevertheless, as familiarity with different crop requirements 

 increased, improvement in planting and care of the land has resulted. 



Methods Employed 



As far back as Roman times, agriculture was well advanced, for the 

 Roman farmer plowed, fertilized, and irrigated his land. Later, un- 

 der the feudal system of the Dark Ages agriculture declined for the 

 reason that the peasants were uneducated and their lords interested in 

 war rather than in the pursuits of peace. It was not until the coming 

 of the eighteenth century that revolutionary changes began to take 

 place in agricultural methods through the practice of crop rotation, 

 and the growing of such crops as would pro^'idc food for stock during 

 the winter season. Agriculture at the present time has become a 

 science, and should be looked upon as a profession. Knowledge 

 necessary to increased crop or stock production is disseminated 

 through various channels, such as farm bureaus, the publications of 

 the Department of Agriculture, various state agencies such as agri- 

 cultural schools and colleges, the public school, and public press. The 

 application of science to disease in both animals and plants has played 

 an important part in promoting agriculture and animal husbandry, 

 as is seen in the successful battle waged against many plant and animal 

 parasites. The science of entomology aids the farmer by furnishing 

 him with the knowledge of life histories of insects, of their methods of 

 feeding, and of their natural enemies, indigenous or imported. Ani- 

 mals and plants introduced from the far corners of the earth have 

 been made available with resulting benefit to the farmer. 



It should be noted that relatively little advance in plant and animal 

 improvement would have been possible had it not been for the applica- 

 tion of certain scientific principles explained in other pages of this 

 book. Although man had bred plants and animals for many thou- 

 sands of years, it had been a very unscientific procedure, conducted by 

 a " hit and miss " method. Long before the rediscovery of Mendel's 

 laws in 1900, man had used selection to improve his stock and nature 

 had helped by occasionally producing hybrids which could be propa- 



