BLACK TERMITE OF CEYLON. 401 



until the afternoon to secure a favourable light, and in the 

 meantime it was completely washed away by a heavy shower. 

 That was in September, 1910. On my return to Ceylon in 

 November, 1911, the nest was found to be in a similar condition 

 to that of the previous year. The heavy rams of the north-east 

 monsoon had washed away almost the whole of the external 

 structure, and the insects were busy re-buildmg it. In that 

 they made very little progress, because the rains every day 

 destroyed what they had just added. The photograph on 

 PL X. was taken on November 27. The opening of the nest 

 is near the top, where the work is most advanced. Below that 

 the plates are arranged in more or less vertical rows. These 

 plates appear broader than they really are, because the termites 

 have already begun to roof over the spaces between them by 

 building out laterally from the outer edge of each plate. In 

 that way the spaces between the rows become the main 

 galleries of the external structure, while the openings between 

 the plates in each row serve as communications between these 

 galleries. 



By December 1 the roofing of the galleries had been com- 

 pleted over half the total area, but on the following day the 

 whole structure was again washed away. That sequence of 

 events — reconstruction and immediate destruction — continued 

 throughout December, until December 29, when the rains 

 practically ceased. On December 29 the structure was in the 

 same stage as on November 27. By January 2, 1912, the 

 galleries had been completed over two-thirds of the total area. 

 The work then progressed much more slowly, and reached the 

 stage illustrated on PI. XI. on January 10. In that stage the 

 external mass consists of one layer of galleries, i.e., of one 

 story only, though the " story " is vertical, not horizontal. 

 But the termites have already begun to add another layer. 

 Here and there may be seen holes in the otherwise continuous 

 surface. Through these the termites emerge and build an 

 elongated enclosure, open at the lower end, which is immediately 

 roofed over. These subsequent additions are made without any 

 such regularity as governed the construction of the first layer. 



It may be noted that building was carried on throughout the 

 day, even in full sunshine. The photographs were taken in 



