402 PETCH : 



full sunlight, but in spite of that the insects are to bo seen at 

 work, though not very distmctly owmg to the long exposure 

 necessary. 



PI. XII. shows the stage reached on January 26. There is 

 very little mcrease in the thickness of the structure, the 

 additions being chiefly vertically doAvnwards in the form of 

 three stalactitic projections. At this stage the openings 

 round the base of the mass, i.e., on the surface of the tree, were 

 closed, so that the only exits were situated on the projections, 

 except for a few openings on the general surface ^here some 

 desultory building was contmued. It will be noted that the 

 surface is cracked, chiefly horizontally, through drying. 

 During February these projections were still further extended, 

 and at the same time the insects began another black structure 

 round an opening four feet lower down the stem. The photo- 

 graph on PI. XIII. was taken on February 21 ; the third 

 projection, on the extreme left, had fallen off shortly after 

 midday on that date. The rainfall durmg January and 

 February had been exceptionally small, but on February 29 

 a shower of several hours' duration, totalling altogether 0-37 

 inch, occurred, which washed away the external structure 

 almost completely, leavmg the termites in a much worse 

 position than on November 27 — that is, presummg that this 

 structure is of some use to them. 



Escherich has suggested that the excrement of Eutermes 

 monoceros differs from that of other termites m some respect 

 which makes it unsuitable for use in the construction of the 

 nest, or that it probal)ly contains some substance which renders 

 its presence in the nest injurious to the insects ; on these 

 NU])p()siti()ns the external structure is merely a mode of dis- 

 l)osing of excrement rejected for hygienic reasons. But these 

 HUggt'stions ignore the fact that the true nest, i.e., the comb 

 within the hollow stem, is also built of excrement which differs 

 only in consistency from that which is, on this theory, rejected. 



Another fact which prevents the adoption of the theory that 

 the e.\t<'rnal mass is merely a method of getting rid of surplus 

 njal<Mial was fnrnished by the nest just referred to. During 

 tin- re-construction of the external mass in December, 11)11, 

 the insects employed not only pellets of excrement, but minute 



