POSSIBILITIES OF ECONOMIC BOTANY. 213 



interest in this subject, and how wide is the field in onr own 

 country for the introduction of new tanning plants. 



It seems highly probable, however, that artificial tanning sub- 

 stances will at no distant day replace the crude matters now 

 employed. 



VII. Resins, etc. — Resins, oils, gums, and medicines from the 

 vegetable kingdom would next engage our attention if they did 

 not seem rather too technical for this occasion, and to possess an 

 interest on the whole somewhat too limited. But an allied sub- 

 stance may serve to represent this class of products and indicate 

 the drift of present research. 



India Rubber* — Under this term are included numerous sub- 

 stances which possess a physical and chemical resemblance to each 

 other. An Indian Ficus, the early source of supply, soon became 

 inadequate to furnish the quantity used in the arts even when the 

 manipulation of rubber was almost unknown. Later, supplies 

 came from Hevea of Brazil, generally known as Para rubber, and 

 from Castilloa, sometimes called Central American rubber, and 

 from Maniliot Glaziovii, Ceara rubber. Not only are these plants 

 now successfully cultivated in experimental gardens in the tropics, 

 but many other rubber-yielding species have been added to the 

 list. The Landolpliias are among the most promising of the 

 whole : these are the African rubbers. Now, in addition to these, 

 which are the chief source of supply, we have Willughbeia, from 

 the Malayan Peninsula, Leuconotis, Chilocarpus, Alstonia, Fors- 

 teronia, and a species of a genus formerly known as Urostigma, 

 but now united with Ficus. These names, which have little sig- 

 nificance as they are here pronounced in passing, are given now 

 merely to impress upon our minds the fact that the sources of a 

 single commercial article may be exceedingly diverse. Under 

 these circumstances search is being made not only for the best 

 varieties of these species but for new species as well. 



There are few excursions in the tropics which possess greater 

 interest to a botanist who cares for the industrial aspects of plants 

 than the walks through the garden at Buitenzorg in Java and at 

 Singapore. At both these stations the experimental gardens lie 

 at some distance from the great gardens which the tourist is ex- 

 pected to visit, but the exertion well repays him for all discomfort. 

 Under the almost vertical rays of the sun are here gathered the 

 rubber-yielding plants from different countries, all growing under 

 conditions favorable for decisions as to their relative value. At 

 Buitenzorg a well-equipped laboratory stands ready to answer 

 practical questions as to quality and composition of their products, 

 and year by year the search extends. 



* See note (*), p. 11. 



