INTRODUCTION 297 



vation of domesticated animals. The work of the farmer, 

 therefore, is plant and animal cultivation, and it is the most 

 important work in the world on the side of our material needs, 

 for upon the results of this work the human population is 

 absolutely dependent. 



In addition to field crops, which are generally referred to 

 under the head of agriculture, and which are chiefly the 

 cereals, there are the so-called garden crops, which include 

 a great variety of plants. " Garden-cultivation " is horti- 

 culture, and it has come to include the cultivation of fruits, 

 of vegetables, and of flowers and ornamental plants. In a 

 broad sense, all cultivation of land for producing crops is 

 agriculture, but it is often convenient to distinguish among 

 the crops. For example, although the cultivation of flowers 

 and ornamental plants is usually included under horticulture, 

 it is often referred to as floriculture. 



By whatever names the various kinds of culture may be 

 called, the obvious fact is that ordinary plant culture deals 

 with five large kinds of crops : (1) cereals, (2) forage plants, 

 (3) vegetables, (4) fruits, and (5) flowers and ornamental 

 plants. Attention has been called to the fact that very 

 few plants have been selected for cultivation. It was natural 

 for men to begin with a few plants when agriculture was just 

 starting ; but the descendants of these men have not added 

 as many to the list as would be expected. The wild plants 

 that might be selected from number nearly 150,000 kinds; 

 while the plants cultivated in any extensive way for food 

 hardly number 150 kinds. Either our ancestors were 

 remarkably acute in selecting out all of the very useful 

 plants, or their descendants have failed to take advantage of 

 a wealth of opportunities all about them. 



In the cultivation of plants, the two things to be considered 

 are the plant and the soil. 



4. The plant. After the right kind of plant has been 

 selected, one must know what that plant needs ; not only 



