338 THE WONDER OF LIFE 



galleries, with fungus-growing labyrinths, but no hills. 

 The soldiers are very large and aggressive, and when dis- 

 turbed make a prolonged noise like the crackling of withered 

 leaves when one treads on them. It is produced by 

 raining tiny blows on the dry surface of the fungus-laby- 

 rinths. 



This type of signal is to be distinguished from another 

 kind, a soundless signal, by which the soldiers seem to 

 give orders to passing workers. The insect, firmly poised 

 on its legs, with the head raised and the body slightly 

 oblique, shakes itself for an instant convulsively. It 

 signals with a shiver. This is probably very common 

 among Termites, and is particularly well illustrated in 

 Eutermes, a genus in which the structure of the soldier's 

 head is not suited for drumming. It need hardly be said 

 that the signalling noise, which is of much psychological 

 interest, is not to be confused with a more commonplace 

 sound of minute grating which is often heard in the 

 silence of the night. That is the sound made by the 

 Termites as they chew. 



If the signals of the soldier-Termites are to be effective, 

 they must be heard or felt, and this is borne out by 

 observations in the field, by the answers that the tenants 

 of Bugnion's desk made to taps from without, and by the 

 anatomical demonstration of a well innervated organ 

 which is probably peculiarly sensitive to vibrations. That 

 the signalling is signalling seems indubitable, and it must 

 be regarded as analogous not so much to the love-signals 

 of the death-watch, who taps on the wainscot, as to the 

 thumps on the ground by which rabbits indicate the 

 approach of danger. 



