THE DISEASES OF THE SUGAR-CANE. 473 



sereh in Java ; in Mauritius the Bamboo cane is most liable 

 to gumming ; while in the West Indies it is the much es- 

 teemed Bourbon which is principally threatened by the 

 rind-fungus. In each case the predominant cane is most 

 attacked. Each of these three is a "soft" cane. What 

 are the characteristics of such a cane ? Large, free-grow- 

 ing, juicy, of great saccharine content, and readily torn by 

 the teeth. 



In India the paunda or native forms are much the 

 hardiest ; in Java the seedling canes more nearly approach- 

 ing the Glagak or wild indigenous kinds are free from 

 disease. From this it is easily gathered that the less hardy 

 canes are the outcome of the most careful human selection. 

 Canes left more to themselves and the action of natural 

 selection are invariably better able to resist disease. An 

 interesting example of this is met with in the canes grown 

 in India — probably near to, if not itself, the original habitat 

 of the species. The forms cultivated may be roughly 

 divided into two classes — those used in the production of 

 sugar and those eaten as a fruit. The former are small, 

 hard, not very juicy, and are left more or less to themselves 

 at a distance from the houses. The latter are thick, juicy, 

 with a thin rind ; they are planted carefully near the houses, 

 and treated to a garden cultivation. The human selection 

 by which these "soft" varieties have been produced has 

 been one-sided ; it has to a great extent neglected liability 

 to disease. Consequently these canes are severely attacked 

 the moment they are left to themselves, and in the field 

 are utterly unable to compete in hardiness with commoner 

 kinds.^ 



This agrees very well with the remark that liability to 

 disease results from an accumulation of certain of a plant's 

 many characters, and that there are all stages between 

 healthy and diseased plants.^ 



13, Attention has already been drawn to the fact that 



canes are found to be of stronger growth if the plants are 



occasionally brought from a distance, on the principle that 



plants, as well as animals, are all the better for an occasional 



1 Watt. 2 Sorauer. 



