284 aNjStual eepoets of depaetment of agriculture. 



against an interruption of supplies from the East Indies by pro- 

 tecting the native gro\Yth of rubber in the forests of unoccupied 

 regions or by planting waste lands. No assurance can be given of 

 the time that will be required to develop practical S3'Stems of com- 

 mercial production in America or that direct competition with the 

 East Indies will become practicable. Premature efforts to promote 

 commercial plantings could only react unfavorably, but the outlook 

 toward commercial planting would be improved by the experience 

 that would be gained in establishing rubber reserves in the Canal 

 Zone or in other accessible regions of tropical America. 



Reforestation with plants containing rubber. — The need of re- 

 claiming and reforesting waste lands in tropical America is being 

 recognized in several countries, and the use of rubber trees or plants 

 for this purpose is being considered in the study of rubber-produc- 

 tion problems in tropical America. The primitive milpa system of 

 agriculture, of cutting and burning new tracts of forest every year 

 to plant corn or other annual crops, as generally practiced in tropical 

 America, is destructive and tends gradually to replace the forests b}'^ 

 low brush or open fire-swept grasslands. Large areas of waste lands 

 are found in many parts of tropical America as a result of the use 

 of the destructive milpa system. The reclamation of such lands may 

 be possible through the planting of rubber or other tree crops to 

 replace the grass or scrubby growth of bushes. Systems of agricul- 

 ture must be taken into account as well as the natural conditions 

 in considering the productive possibilities of a country for rubber 

 or other crops. 



EXPLORATIONS AND PLANT INTRODUCTIONS. 



SEARCH FOR FOREIGN CEREALS AND FRUITS. 



During the past year Joseph F. Rock, agricultural explorer for 

 the bureau, has traveled in the remote Province of Yunnan, South 

 China, and in the neighboring portions of Burma. From this little- 

 known corner of the world he has sent to the United States seeds of 

 many new pears and apples likely to prove of value in this country 

 as stocks upon which to graft American varieties, as well as many 

 other native fruits and ornamental plants. From Burma he sent 

 several thousand seeds of Taraktogenos hurzii.^ a tropical tree whose 

 seeds yield chaulmoogric acid, successfully used in the treatment of 

 leprosy. The plants grown from this shipment will be sent to Ha- 

 waii and other regions where leprosy is present. In January, 1923, 

 Mr. Rock entered into an agreement with the National Geographic 

 Society, which undertook to maintain him in the field for another 

 year. During this time Mr. Rock, who remains on the department 

 rolls as a collaborator, sends his collections of seeds and plants to 

 this bureau. 



Dr. H. V. Harlan, engaged in cereal investigations, was sent to 

 North Africa and India in search of barleys. His collections of 

 seed, including many varieties of wheat and barley, are expected 

 materially to enlarge the range of types of this crop for agronomic 

 testing and for breeding work. 



