CHAPTER XIX 

 PLANT INDUSTRIES 



292. Origin of plant cultivation. In the various chapters of 

 this book we have constantly recognized the relation of plants 

 to the common interests of men. It is important, however, 

 that special uses of plants in the industries should receive 

 separate attention. 



In the early stages of civilization plants were used by men 

 for food, clothing, and fuel, for the construction of houses 

 and boats, and in many other ways. In order to obtain those 

 plants that would best serve any of these uses, some obser- 

 vation and experiment with plants doubtless had to be made. 

 Indeed, primitive people are often well versed in the nature 

 of wild plants, so that they know what to select and where 

 to find the desired plants in the seasons when they are avail- 

 able. Wild plants that were good for food or possibly for 

 medicines were cared for early in the history of civilization. 

 We can only guess at the ways in which they were first 

 watched and protected, but they were cared for by people who 

 foresaw a need for the products of these plants when mature. 

 With such activities as these agriculture came into existence. 

 At this time comparatively little was known of the nature of 

 plant life, and therefore early agriculture was relatively simple. 

 As more has been learned about plant life, plant products have 

 improved in quality or in quantity, or in both. As populations 

 become more dense, greater demands are made upon plants 

 as a means of supplying adequate food and clothing. 



293. Problems of plant industries. Each of the plant indus- 

 tries involves two kinds of problems. First, there is the prob- 

 lem of carefully applying what science has already discovered 



