CONSTITUTION AND DEVELOPMENT OF TERMITES. 255 
will therefore appear to run in the sound structures. But, so 
far as I have observed, this lining of decayed tissue is never 
absent. 
It is undeniable that the process of decay is hastened by 
these burrows, particularly because they allow the infiltration 
of rain-water ; but a detailed study of these phenomena would 
lead too far from the subject. 
Calotermes greatly prefers to live in the deepest parts of 
the dead wood,—that is, the parts nearest the living tissues, 
and consequently the most recently decayed. Portions which 
have been long dead are usually too dry for it, and are chosen 
as a tenement by ants. 
Fertile pairs, unaccompanied by eggs or with very few 
offspring—that is to say, nests in process of formation or 
recently formed,—are to be found by special search at the 
places where a plant has been pruned a year or two previously 
and has subsequently rotted, provided that the pruning has 
not followed on antecedent decay. ‘This can be easily observed 
in the fig or vine. Fresh nests, therefore, are usually estab- 
lished where the dead portion is still so limited in extent as 
not to afford space for a numerous colony, and these situations 
are rarely preoccupied by other insects, such as ants, beetles, 
or other Termitide, &c. As the colony gradually increases 
and requires more room, the decayed area spreads, but to all 
appearance independently of the insects. That this is the 
case is rendered probable by an examination of progressive - 
decay in a district where Calotermes is absent, such as 
Lombardy, where the winter is too severe for them. 
Turning once more to the formation of the fresh termitaria, 
I do not wish to deny the possibility of its taking place in 
trunks in which extensive decay already exists; but such an 
occurrence is unusual, either because the wood is preoccupied 
by termites or other insects, or because the royal pairs must 
traverse parts which are already dry and swarming with enemies 
(ants), in order to arrive at the required spot where the decay 
is most recent. 
The corks of the tubes are attacked probably because they 
