FIFTEENTH ANNUAL REPORT 51 



(Manihot utillissima Poir.), and tapioca. Among other possible sources are 

 arrowroot (Maranta arundinacea Linn.) ; sincamas (Pachyrhizus erosus 

 Urban) ; Polynesian arrowroot {Tacca pinnatifida Forst.) ; yams (Diosco- 

 rea) ; seeds of Cycas circinalis Linn.; and the sugar palm {Ay'enga saccha- 

 rifera Labill.). 



Dye materials. — Natural vegetable dyes are used locally. The present 

 production is of slight importance. 



REFERENCES 



The enzymes of cacao, Philippine Journal of Science, Sec. A (1915), vol. 

 10, No. 2, 123-133. 



Papain; its commercial preparation and digestive properties, Phil. Journ. 

 Sci., Sec. A (1915), vol. 10, No. 1, 1-35. 



Starch production in the Philippine Islands, Phil. Journ. Sci., Sec. A 

 (1908), vol. 3, No. 2, 93-97. The alcohol industry of the Philippine Islands, 

 Phil. Journ. Sci., Sec. A (1911), vol. 6, No. 3, 147-206. 



The physiologically active constituents of certain Philippine medicinal 

 plants, Phil. Journ. Sci. (1906), vol. 1, No. 10, 1007-1036. 



The natural dyes and coloring matters of the Philippines, Phil. Journ. 

 Sci., Sec. A (1910), vol. 5, No. 6, 439-452. Philippine natural dyestuff 

 materials, Bureau of Science press bulletin 52, June, 1916. 



PHILIPPINE BUREAU OF SCIENCE CHART 6 



TANNING AND PAPER-PULP MATERIALS 



[See prints in photograph stand.] 



Tan bark. — The area of the mangrove swamps of the Philippine Islands 

 is estimated to be 207,000 hectares (511,500 acres). The bark from the 

 mangrove yields an excellent tanning material. Cutch, the evaporated 

 water-extract of tan bark, is imported into the United States in large quan- 

 tities. Bark from the better species of Philippine mangrove trees contains 

 30 per cent of tannin. A net profit of from $25 (?50) to $30 (?60) per 

 ton can probably be made on tanning material derived from the mangrove 

 swamps in the Philippine Islands. Firewood and the products of wood 

 distillation could be made in connection with the cutch industry. The bark 

 of Benguet pine and of palo maria can also be utilized as tanning materials. 

 Forest regulations prevent the cutting of palo maria exclusively for its 

 bark. 



Paper pulp. — One of the bamboos, known as cafia bojo, has been shown to 

 be especially suitable for the making of paper pulp; it grows in sufficiently 

 large and pure stands to make possible the commercial pi'oduction of paper 

 pulp. Abaca waste, cogon, talahib, rice straw, etc., are other materials 

 from which the Bureau of Science has made strong paper pulp and which 

 it should be possible to utilize commercially for the same purpose. 



REFERENCES 



The economic possibilities of the mangrove swamps of the Philippines, 

 Philippine Journal of Science, Sec. A (1909), vol. 4, No. 3, 205-210. Phil- 

 ippine firewood, Phil. Journ. Sci., Sec. A (1911), vol. 6, No. 1, 1-22. The 

 economic possibilities of the mangrove swamps of the Philippines, Phil. 

 Journ. Sci., Sec, A (1911), vol. 6, No. 1, 45-61, The leather industry of 

 the Philippine Islands, Phil. Journ. Sci., Sec. A (1915), vol. 10, No 6, 



