258 B. GRASSI AND A. SANDIAS. 
barricades of masticated wood, or more commonly of excre- 
ment, which is cemented together by saliva, with or without an 
admixture of disgorged wood. This disgorgement is normal, 
and not exceptional, as Fritz Miller believes. 
The following facts and other details of interest may be 
easily observed through the glass tubes. 
If some fragments of wood and a few Calotermites are 
put into a tube and left uncorked, the insects will be found 
on the following day to have established themselves either in 
the whole of the space filled with wood, or in its lower por- 
tion, at the bottom of the tube. In either case the occupied 
area is delimited by means of disgorged matter deposited in 
the interstices between the particles of wood. As far as can 
be seen the boundary wall is complete, but it lies at different 
levels and not entirely in the same plane; its margin can 
easily be made out at the point of contact with the glass, and 
will be found on revolving the tube to form a complete circle, 
but with some irregularities of level, obviously due to a 
selection of the smallest interstices for cementing up without 
reference to their higher or lower elevation. 
[The process of construction can be watched in the tubes ; 
the insect regurgitates a pasty mass, which is spread out, if 
necessary, by the antenne, so as to form a rounded pellet on 
the glass of about a millimetre in diameter, and of the colour 
of rotten wood. | 
The boundary wall is undoubtedly designed for protection 
against direct contact with the atmosphere ; this is proved by 
its not being constructed if the tube_is closed with a cork 
instead of remaining open. 
Such a wall may occasionally be built even in a corked 
tube, should part of the nest contain any offensive substance. 
Thus if flour be added to a small tube-nest, after a few days 
the upper part containing the flour, which will have become 
mouldy, is found to be cut off in the manner described’from 
the lower portion, in which all the insects have collected. 
Sometimes the Calotermites,in a tube may be seen to cement 
1 [‘ Jen.®Zeitschr.,’ vii, p. 3438.] 
