XV, 4 
Oshima: Formosan Termites 
337 
Damage to brick walls. — There are several records in For- 
mosa of modern brick buildings having been infested by 
Coptotermes formosanus. It is absolutely impossible for it to 
attack brick itself; but, according to my actual observation, 
the mortar which is used as a cementing material for bricks 
is subject to attack. 
In building a thick brick wall the following method is adopted : 
The face bricks are laid upon a bed of mortar; the mortar, 
in a semifluid condition, is then poured into the space between 
the face bricks ; the bricks are then pushed rapidly, horizontally 
for a short distance, into their position; a certain amount of 
the mortar is thus displaced; this rises in the side joints and 
completely fills all the interstices; should the mortar not rise 
to the top of the joints, the vacant spaces are filled up, when the 
next course is larried. 
All the interstices between the bricks would be completely 
filled, if the bedding could be carried on theoretically; but this 
is practically impossible, so that there are almost sure to be 
voids in brick walls. Under such conditions, termites prefer to 
pass through brick walls, if they have a chance to permeate 
them, rather than to excavate ordinary walls; because the voids 
are always in a favorable condition for their life, being pro- 
tected from the sunlight and containing a proper amount of 
moisture. 
There are two kinds of mortar used for constructional work; 
namely, cement mortar and lime mortar. The former i3 com- 
posed of sand and Portland cement (the ratio of Portland 
cement to sand is from one to two to one to four), while the 
latter is composed of moderately hydraulic lime and sand (the 
ratio of lime to sand is usually one to two). 
In Formosa until a comparatively recent date lime mortar was 
exclusively used for the bedding of bricks. It has been found, 
however, that Coptotermes formosanus easily penetrates brick 
buildings and causes serious damage (Plate VII). Since the 
Government has required the use of cement mortar instead of 
lime mortar there has been no record of damage to brick walls. 
Therefore, it seems reasonable to conclude that there exists 
some special relationship between lime and the destructive power 
of Coptotermes formosanus. 
The soldier of Coptotermes formosanus is provided with a 
special gland on the forehead, which secretes a milky, acidulous 
fluid; its excreta and saliva are also acidulous, while those 
of the worker are alkaline. In the passages perforating the lime 
