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through brick walls, if they have a chance to permeate them, 

 rather than to exca\ate ordinary walls ; because the voids are 

 always in a favorable condition for their life, being protected 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 is 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 Coptotcnncs fonnosanits easily penetrates brick 

 buildings and causes serious damage. 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 formo- 

 sanus. 



The soldier, of Coptotermes fonnosanus 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 mortar 

 of brick walls vast numbers of soldiers are found. Such being 

 the case, it is said that the soldier of Coptotermes formosanus 

 attacks lime mortar by dissolving the lime with the acidulous 

 secretions. 



Damage to ralhuay sleepers. — Coptotermes formosanus attacks 

 railway sleepers as well as buildings. According to a statement of 

 the Bureau of the Formosan Government Railway, the life of an 

 untreated, chestnut sleeper is only two years in Formosa, while in 

 Japan proper it is from eight to ten years. 



In the southern part of Formosa another species of termite, 

 Odontotermes formosanus, also attacks the sleepers. 



The damage it causes is rather more serious than that caused 

 by Coptotermes formosanus. Therefore, in the case of sleepers, 

 it is important to prevent the damage caused by these two species. 

 Usually the length of the spike which is used to fix the rail to a 

 sleeper is a little greater than the depth of the latter, so that its 

 tip always penetrates beyond the bottom of the sleeper, causing 

 some damage to that surface. This point is most liable to be at- 

 tacked. As the pests excavate the wooden tissue surrounding the 

 spike, the latter becomes ineffective. Suppose such damage occurs 

 successively in several sleepers ; the results are quite obvious — the 

 rails spread and cause great danger to passing: trains. 



Damage to ships. — One can hardly believe that steamships 

 and launches in the water have been attacked by Coptotermes 

 formosanus; but it is an undeniable fact. There are many records 

 of such cases in the harbor of Keelung, Forn;osa. It happens in 

 this way. In the swarming season, many thousands of winged 



