226 The Philippine Journal of Science 1921 
the Philippines, but none commensurate with those in Brazil, 
described by Branner. 
The writer’s attention has just been called to the very inter- 
esting investigations of Oshima*® on Formosan _ termites 
wherein he states that Coptotermes formosanus secretes a 
milky, acidulous fluid which dissolves the lime in the mortar 
of brick buildings. In order to protect the buildings he advises 
the construction of a concrete basement floor which shall have 
as few seams as possible. 
It also appears from such studies as have been made that 
certain termites occupy in the Tropics a place analogous to that 
filled by the common earthworms in temperate regions. 
An instance of the work of winds and plants in combination 
may be of interest. In the recent destructive typhoon which 
struck Manila with such force (September 1, 1920), a great 
many of the fine acacia trees, which are the principal shade 
trees of the city, were uprooted and many sections of cement 
sidewalk were badly damaged as a result. These trees have 
widely ramifying and very shallow roots, with no tap root; 
consequently, with their wide-spreading tops, they became easy 
victims of the storm. 
Corals.—The réle that corals and coral reefs play in matters 
of engineering and the economic development of a country can- 
not be overlooked. We have already alluded to the connection 
between coral formations and water supply. Coral limestone 
is a very important source of construction material. In certain 
other ways coral formations are of great importance. For 
instance, the fringing reefs protect the shore from storm waves; 
also, they afford a firm foundation for future land when covered 
with earth, either naturally or artificially. Most of the 
coastal plain tracts in the Archipelago have a coral foundation 
which is much more stable than is mere alluvium. 
STRUCTURE 
Much has been written in the textbooks about structure, and 
most engineers are probably cognizant of the importance of 
this branch of geology, but as yet little has got into the literature 
concerning this subject in tropical regions. Naturally an en- 
gineering feat of the magnitude and importance of the Panama 
Canal would necessitate a most careful regard for anything which 
might have an effect upon both the task of construction and the 
* Oshima, M., Formosan Termites, Philip. Journ. Sci. 15 (1919) 319. 
