282 ANNUAL, REPORTS OF DEPARTMENT OF AGRICULTURE. 



salts in the soil, especially if these accumulations are high in sodium 

 compounds. It appears reasonable to expect that even where irri- 

 gation water contains relatively high percentages of sodium salts 

 more liberal use of water and more adequate drainage may prevent 

 dangerous salt concentrations. 



SOURCES OF CRUDE RUBBER. 



On the basis of a special appropriation for this purpose, more 

 extensive investigations of rubber-producing plants are being under- 

 taken to determine the possibilities of producing rubber in the 

 United States or in adjacent tropical regions. The need of develop- 

 ing other sources of supply is shown by the rapidly increasing con- 

 sumption in the United States and the danger of supplies from the 

 East Indies being interrupted. About nine-tenths of the world's 

 supply of crude rubber now comes from the East Indian plantations, 

 and about three-fourths of the total supply is used in the United 

 States. Exploring parties have been sent into Central America and 

 South America during the past j-ear to consider both species now 

 known commercially as more or less satisfactory for producing rub- 

 ber and to assemble such other plants containing rubber as may give 

 promise of experimental development. 



Ivvestigations of Para I'^hher in South America. — An expedition 

 has been organized to visit the native rubber forests of Brazil and 

 those of the upper valley of the Amazon in Peru and Bolivia to 

 obtain more definite information regarding the habits and geo- 

 graphic distribution of the Para rubber tree {Hevea hrasUiensis) 

 and to procure seeds or propagating material of superior stocks of 

 this or other species of Hevea that are likely to be more productive 

 or more tolerant of drought or other unfavorable conditions. 



Ruhher exferhnents in Haiti. — About 150 acres of different kinds 

 of rubber-producing trees were planted about 20 years ago (1903 to 

 1905) in the district of Bayeux, near the north coast of Haiti, where 

 they are being utilized for shade in a cacao plantation. These 

 plantings indicate that the local conditions are not unfavorable for 

 the growth of the trees, though tapping has not been done in a 

 manner that would determine the possibilities of commercial pro- 

 duction. The plantings include two species of Castilla, with Hevea, 

 Funtumia, Ficus, and Mimusops. 



Hahits of the Funtumia rvhher tree. — The behavior of the Fun- 

 tumia rubber tree in Haiti shows several desirable features that may 

 render it especially adapted for use in reforestation or rubber re- 

 serves, if not for commercial planting. The seeds have a large 

 pappus and are carried by the wind, while the seedlings are tolerant 

 of shade and able to grow in competition with other vegetation in 

 waste places. Trees that are cut sprout vigorously from the stumps. 

 The trees are vigorous and the foliage is clean and attractive, not 

 unlike that of coffee. The leaves stand opposite but are slightly 

 unequal in size ; but the flowering and branching are alternate, only 

 one leaf of each pair producing an inflorescence or a leafy branch. 

 Seed is produced abundantly from large double pods. Rubber can 

 be obtained by mechanical extraction from the dry bark of Funtumia 

 as well as from the latex. 



