Human Factor in Plant Evolution 281 



Antiquity of Certain Cultivated Plants. As far 

 back as history runs we encounter evidences of the 

 cultivation of many food and textile plants still in 

 use. This is true in Egypt, China, and India, and 

 in the New World the advanced civilization shown 

 by remains of man in Peru and Mexico, show that 

 agriculture had reached a high degree of perfection 

 at a very remote period. Among the most inter- 

 esting evidences as to the early cultivation of many 

 useful plants in prehistoric times, are the remains 

 of the Swiss Lake-dwellers. At a period when 

 these ancient people still used only stone implements, 

 they cultivated a variety of food plants, including 

 wheat, barley, and millet, and they also grew flax. 



First in importance among cultivated plants are 

 those grown for food, and among these the various 

 grains take first place, followed by certain fruits; 

 but other parts of the plants the leaves, roots, or 

 tubers may also be important sources of food. 

 Next in importance are plants furnishing fibers, usu- 

 ally derived from stems or leaves, the most im- 

 portant exception being cotton, which furnishes a 

 fiber attached to the seed. Some of these fiber 

 plants, especially flax and hemp, have been cultivated 

 from the earliest historical times, but the history 

 of some of the less familiar fibers, like jute, Manila 

 hemp, and ramie, is very imperfectly known. 



It is probable that very early in his history, man 

 learned the virtues of certain medicinal plants. In 

 his search for food plants he doubtless, through 



