260 MATERIAL PROGRESS 



have disappeared from the wild flora of the earth. 

 No wild progenitors can be indicated with any 

 certitude for maize, the millets, wheat, barley, 

 rye, oats, beans, lentils, yams, sweet potatoes, 

 and sugar cane. On the other hand, rice, cotton, 

 potatoes, tobacco, and the various root-crops can 

 be traced to plants that still occur in a wild state. 

 When grain-yielding plants had been brought 

 under control the advantage would be perceived 

 of growing oilseeds to provide a relish in diet and 

 a means of lighting ; also of growing fibres, the 

 usefulness of which was enormously increased by 

 the invention of the loom as a substitute for 

 finger-plaiting. If diversity of crops may be taken 

 as an indication of antiquity, it was in sub-tropical 

 Asia that agriculture achieved its first develop- 

 ments. The principal cereals of European agri- 

 culture are exotics : wheat and barley were 

 originally Asiatic, and it was not until the Arab 

 conquests of the seventh and eighth centuries 

 that cotton and sugar cane became known in the 

 Mediterranean. Maize, potatoes, the haricot 

 bean, and tobacco are heritages from the culti- 

 vators 01 Mexico and Peru. But Europe has 

 specialities of its own root crops, in particular, 

 such as the turnip, the swede, and beet, which will 

 not flourish outside the temperate zone. 



In the development of mechanical art European 

 civilization incomparably surpasses that of Asia. 

 There is no such difference in regard to agriculture. 

 The cultivation of Egypt, of Mesopotamia, China, 

 and India, reached a very high standard of 

 excellence : plants were differentiated into a vast 

 number of varieties indeed, over 700 kinds of 

 rice are grown in India : the value of manuring 

 and of rotations was fully appreciated. Modern 

 science has ascertained that leguminous plants, 

 through the agency of microbes which form 



