The above remarks apply more especially to the larger of the two white ants of Southern Europe. In regard to the smaller one, Professor Grassi makes the following interesting remarks: “Termes makes the same convulsive movements as does Calotermes, but the soldier of this species is able to produce a special creaking sound, which arises, whenever the head is held horizontally, during the act of quivering, by friction between the back of the head and the front part of the thorax. But whenever the head, during this act, is held in the usual position, which is not quite horizontal, no perceptible sound is produced, owing to the absence of such friction. The soldiers of Termes, therefore, possess two distinct modes of communication, whilst those of Calotermes have only one, in which no perceptible sound is produced. This characteristic _crepitus_,” continues the Professor, “may be heard, at frequent intervals, by applying the ear to a tube containing a nest of Termites. This proves that the quivering motions are a constant feature in undisturbed nests, so that they cannot be employed only as signals of alarm or distress. I conclude, therefore, that besides such special significations these convulsive movements must also have the value of ordinary speech; that they constitute, in short, a means of intercommunication. The same conclusion holds good for Calotermes (the one we have hitherto been talking about), and I imagine that the quivering of both species produces a sound which is perceptible to the insects themselves, but inaudible to the human ear.”[9]