TWELFTH ANNUAL REPORT 25 



can be killed by fumigation with carbon bisulphide or hydro- 

 cyanic acid gas. 



26. Garden and field crop insects. — A very large amount of 

 miscellaneous information is on record in this Bureau and has 

 been disseminated regarding the prevention of the ravages of 

 pests of garden products, such as, cabbage, asparagus, camotes, 

 peas, corn, beets, radishes, and cucumbers ; and the many purely 

 native crops, such as, gahi, ubi, camoting-cahoy, calahasa, and 

 upo. 



27. Silk culture. — This Bureau introduced the culture of the 

 polyvoltine silkworm of Ceylon in the Philippine Islands, and, 

 besides developing a Philippine race producing at least eight 

 generations a year, has definitely established the fact that the 

 Japanese monovoltine silkworm cannot be acclimated here. The 

 eri silkworm will thrive here, and an abundant supply of food for 

 this insect exists in the castor oil plant commonly growing wild 

 throughout the Islands. 



28. Marine biology. — A beginning has been made in the 

 important branch of biology which includes the study of marine 

 products; such as, pearl oysters, window shell, edible mollusks, 

 and edible fishes. A number of important groups of marine 

 animals are being studied systematically, and among the more 

 technical papers on this subject may be mentioned those on 

 the anatomy of Aclesia freeri and of Euplotes worcesteri, the 

 habits of fiddler crabs, and the descriptions of new species of 

 fishes. When a sufficient amount of systematic work has been 

 completed, we shall have a substantial basis for extended economic 

 work and for the development of the fisheries industries. 



29. Fishery resources. — The fishes commonly used as food have 

 been identified; and their abundance and value noted. 



A study has been made of the varieties of commercial sponges 

 found in the Islands, and suggestions published with regard to 

 their artificial propagation. 



The species of pearl-producing mollusks have been identified, 

 a study has been made of the existing pearling industry, and a 

 modification of existing laws governing pearl fishing has been 

 suggested. 



Other marine products that have been studied include trepang, 

 sharks' fins, tortoise shell, window shell, shells for buttons, 

 precious coral, edible seaweeds, and isinglass. 



30. Ethnology. — Our published researches in ethnology have 

 increased the information concerning the social organizations, 

 languages, beliefs, manners and customs, and the territory 



