20 THE ESSENTIALS OF AGRICULTURE 



it furnishes the man who wishes to experiment, with a scientific 

 basis upon which his experiments may be conducted. 



21. Improved plants and animals require constant care. Plant 

 and animal improvement cannot be made by selection and breed- 

 ing alone. Feeding and care are equally important (Figs. 12 a and 

 12 b). The more highly developed plants and animals become, 

 the more dependent are they upon man. When our agricultural 

 plants grew wild, they were planted by natural means, required 

 no cultivation, and fought their own battles with other wild plants. 

 If they were now left to their own resources, many of them would 



FIG. 13. An improved cow and the calves which her milk might have 

 nourished 



A modem, high-grade cow may give enough milk to nourish fifteen calves. The unim- 

 proved cow gave scarcely enough milk to sustain one calf 



not survive. It is doubtful if our highly developed beef and 

 dairy cattle would survive if left to subsist, unaided by man, on 

 the wild steppes of Russia or in the dense jungles of the tropics. 

 Certainly if they did survive, it would be because they had the 

 power quickly to revert to the unimproved type. They would 

 live because of their power to throw off what man has been 

 centuries in developing. 



This does not mean that improved animals and plants are 

 weaker than their wild ancestors. It means merely that the con- 

 ditions under which wild plants and wild animals live are very 

 different from those under which domesticated forms live, and 



