196 THE SPEECH OF MONKEYS. 



insect life would be as little suited to mammals, 

 perhaps, as the feathers of a bird would be for 

 locomotion in the realm of fishes. 



I am aware that some high authorities have 

 claimed that insects communicate by sounds. 

 My own opinion is that they employ a system of 

 grating or scratching by means of their sigmata, 

 but that the sound created thus performs no 

 function in the act of communicating, but is only 

 a by-product, so to speak, and that the jarring 

 sensation transmitted through the air is the real 

 means by which they understand each other, pos- 

 sibly somewhat like telegraphy, in which the 

 sounds are not modulated, but are distinguished 

 by their duration and the interval between them. 

 I do not announce this as conclusive, but merely 

 suggest it as a possible key to their mode of in- 

 tercourse. 



I have observed that signs prevail to a great 

 extent among ants. Some years ago I had an 

 opportunity of studying a colony of ants, and I 

 watched them almost daily for several weeks. I 

 had seen it stated that they found their way by 

 the sense of smell, but these observations con- 

 firmed my doubts on that point, and I feel justi- 

 fied in saying that they are guided almost if not 



