32 INSECTS INJURIOUS TO FORESTS. 
and figures "sensory hairs"; "sensory pits"; "tibial spurs with 
prominent basal apertures, across which extends a delicate membrane 
(auditory organs?)"; "pilose depressions"; "surface markings"; 
etc. Grassi ° mentions tactile, "very long, fine, readily vibratile 
hairs" on the body, and states that the cerci also appear to be "es- 
sentially tactile." It is believed that there is a relation between the 
convulsive movements frequently observed, that is, the sudden 
jerking of the whole body, and these sense organs, and that indi- 
viduals are thus enabled to communicate, or at least give danger 
or distress signals. The convulsive movements made by the workers 
and soldiers, when the royal pair are disturbed in the cell, are very 
violent and indicate great agitation. 
There is a characteristic musty or acrid odor which can be easily 
detected in colonies of Leucotermes, and individuals frequently 
can be seen to follow directly in the path taken by others, but as 
termites usually travel in well-worn channels this may be due to 
tactile sense alone. 
THE FUNCTIONS OF THE CASTES. 
The social economy of termites is somewhat similar to that of other 
social insects, although in many respects totally different. Undif- 
ferentiated young hatch from the eggs, are active, and in turn trans- 
form to the differentiated individuals of the castes after a series of 
quiescent stages and molts. 
As the name implies, the workers are those individuals that make 
the excavations, extend the colony, and care for and protect the 
royal couples and young. 
The soldiers, more highly specialized workers, are of less importance 
functionally than the workers — just as the anther transformed to the 
petal in the common pond lily, Castalia sp., is less important function- 
ally than the other anthers — yet both serve a purpose. Just before the 
time of swarming, the members of colonies become restless, and as 
the sexed adults emerge numerous workers and soldiers congregate on 
the outskirts of the colony near the exit holes with heads toward the 
exterior. The duty of the soldiers is apparently entirely protective, 
but they do not appear to be very effective, at least when the colony 
is opened and they are exposed to the attack of ants, etc. 
The pigmented, winged, sexed adults, developed from nymphs 
of the first form, are the colonizing individuals which swarm in 
enormous numbers in the spring and found the new colonies, and 
when finally established at the head of a new colony, which they 
have reared, they become the royal couple. Unlike other social 
insects, the male continues to live, even after the fertilization of the 
female, and the king and queen inhabit the royal cell together, there 
a Grassi, B., and Sandias, A. Op. cit., p. 267-269. 
