tts MANGROVE SWAMPS 
In view of the data given above it is not surprising that the 
mangrove-swamp species are highly prized for firewood, that 
the swamps near the centers of population have been largely 
depleted of the more valuable species, and that bakauan is raised 
in plantations. 
TANBARKS 
The mangrove barks constitute the greatest single source of 
tanning material in the Philippines. The species of mangrove 
trees which are used commercially for tanning purposes grow 
in the Philippines in large numbers. The export of mangrove 
tanbarks and of the bark extract, known as cutch, is an im- 
portant industry in some tropical countries. In the Philippines 
this industry has never been developed, and the barks are used 
locally to only a limited extent; although there are extensive 
swamps in the Archipelago. The Philippines possess an ad- 
vantage over such countries as Borneo in that owing to a large 
population the wood can be used as firewood; so that it would 
seem advisable to combine the bark collection with the cutting 
of firewood. 
Extensive analyses of Philippine mangrove-swamp barks have 
been made by Bacon and Gana * and by Williams.+ In Table 
XXIII are given the results of analyses made by Bacon and 
Gana of barks from Mindanao; and in Table XXIV analyses 
of barks from Mindoro made by the same workers. Table XXV 
gives the results of analyses of barks submitted by the Bureau 
of Forestry to the Bureau of Plant Industry at Washington. 
These figures are published by Williams. In Table XXVI are 
given the results of analyses made by Williams. Table XXVII 
shows the results of analyses made on barks from Sarawak, 
Borneo. 

* Bacon, R. B., and Gana, V. Q., The economic possibilities of the man- 
grove swamps of the Philippines, Philippine Journal of Science, Sec. A, 
Vol. 4 (1909), pages 205 to 210. 
+ Williams, R. R., The economic possibilities of the mangrove swamps 
of the Philippines, Philippine Journal of Science, Sec. A, Vol. 6 (1911), 
pages 45 to 61. 
