96 MENTAL EVOLUTION IN MAN. 



Ray observed the different tones used by the common 

 hen, and found them uniformly significant of different 

 ideas, or emotional states ; therefore we may properly 

 regard this as a system of language, though of a very 

 rudimentary form. He distinguishes altogether nine or ten 

 distinct tones, which are severally significant of as many 

 distinct emotions and ideas — namely, brooding, leading forth 

 the brood, finding food, alarm, seeking shelter, anger, pain, 

 fear, joy or pride in having laid an ^%^. Houzeau, who 

 independently observed this matter, says that the hen utters 

 at least twelve significant sounds.* 



Many other cases could be given among Birds, and a still 

 greater number among Mammals, of vocal tones being used 

 as intentionally significant of states of feeling and of definite 

 ideas ; but to save space I will only render a few facts in a 

 condensed form. 



"In Paraquay, the Cebiis azarce when excited utters at least 

 six distinct sounds, which excite in other monkeys similar 

 emotions (Rengger). ... It is a more remarkable fact thati; 

 the dog, since being domesticated, has learned to bark in at 

 least four or five distinct tones : ... the bark of eagerness, 

 as in the chase ; that of anger, as well as growling ; the yelp, 

 or howl of despair, when shut up ; the baying at night ; the 

 bark of joy when starting on a walk with his master ; and the 

 very distinct one of demand or supplication, as when wishing 

 for a door or window to be opened." f 



I may next briefly add allusions to those instances of the 



already recorded in Mental Evohition in Animals (p. 343, note). The animal is 

 the processional caterpillar. These larvae migrate in the form of a long line, 

 crawling Indian file, with the head of the one touching the tail of the next in the 

 series. If one member of the series be removed, the next member in advance 

 immediately stops and begins to wag its head in a peculiar manner from side to 

 side. This serves as a signal for the next member also to stop and wag his head, 

 and so on till all the members in front of the interruption are at a standstill, all 

 wagging their heads. But as soon as the interval is closed up by the advance of 

 the rear of the column, the front again begins to move forward, when the beid- 

 wagging ceases. 



♦ Fac. Ment. des Animaux, tom. ii., p. 348. 



t Darwin, Descent of Man^ pp. 84, 85. 



