Contents 
V 
Page. 
Yates, Harry S. The growth of Hevea brasiliensis in the Philippine 
Islands 501 
One text figure. 
UiCHANCO, Leopoldo B. A biological and systematic study of Phil- 
ippine plant galls 527 
Fifteen plates. 
Cockerell, T. D. A. The sphecodine bees of the Philippine Islands.... 555 
Reviews 559 
No. 6, June, 1919 
[Issued December 16, 1919.] 
King, Albert E. W. The mechanical properties of Philippine bast- 
fiber ropes 561 
Five plates and two text figures. 
Lee, H. Atherton, and Yates, Harry S. Pink disease of citrus 657 
Seven plates and two text figures. 
Errata 675 
Index ^ 677 
