320 



males and femg,les start from the nests in the vicinity of the 

 shore. Some of them have a chance to fly into the ships moored in 

 the harbor and there start new colonies. The interior of the ship 

 is dark enough to favor the establishment of a nest. Usually the 

 bottom of the ship is constructed of Japanese pine, which is m.ost 

 durable in water; all the timbers contain a favorable amount of 

 water. Thus, all conditions being exceedingly favorable to Cop- 

 totcrmcs formosauiis, the ravages are extended step by step, until 

 the vessel becomes unseaworthy, because of the unexpected 

 destruction of important parts of the w^oodwork. In such a case 

 extermination of the pests is very difficult. When the Govern- 

 ment trawler Ryokai-maru was found to be infested, it was pur- 

 posely sunk in the sea in order to destroy the insects. 



Besides the above-mentioned damage, that done to bridges, 

 telegraph poles, books, paper, wood pulp, cotton, and clothing is 

 sometimes very serious. 



TRINCIPAL FOOD OF COPTOTERMES FORMOSAXUS 



The stem of an exogenous perennial is a complex of structural 

 elements of varied form and function. Of these we may dis- 

 tinguish three main groups : a, vessels ; b_, wood cells proper ; c, 

 medullary tissue. The growing cell of plant tissue consists of cell 

 wall and protoplasm, the living functions depending upon the 

 activity of the latter. However, the above-named three main 

 structural elements of the wood do not contain nitrogenous sub- 

 stance — that is. protoplasm — but mainly consist of the special 

 constituent of the cell wall known as cellulose. 



There are, as might be expected, a great many varieties of 

 cellulose, and the term must be taken as denoting a chemical 

 group. Cellulose, taken as a group, presents the following 

 characteristic: A colorless substance, insoluble in all simple 

 solvents; generally but variously resistant to oxidation and 

 hydrolysis ; nunnitrogenous, having the empirical constitution 

 characteristic of the carbohydrates. The composition of pure 

 cellulose is represented by the percentage numbers C 44.2, H 6.3, 

 O 49.5, corresponding to the empirical formula (CcHi„05)x. It 

 is flexible, slightly elastic, permeable, but only slightly absorbent, 

 and does not readily undergo fermentation. When treated with 

 acid it passes into a starchlike condition, as is evidenced by its 

 turning blue with iodine; and under certain conditions in the 

 living plant it would seem capable of being formed from sugar 

 or of passing into it. 



It must be noted, however, that the typical cellulose is not 

 separated from the plant in a pure state, but in admixture or 

 in intimate chemical union wnth other compounds or groups of 

 compounds. The latter are distinguished bv greater reactivity; 

 for example, they readily yield to alkaline hydrolysis, to oxida- 

 tion,' or to the action of the halogens. In the latter is included the 

 very important group of lignified cellulose, or lignocellulose. 



