VARIETIES OF LAUGHTER 207 



social appeal and response. Only in rare cases do people 

 laugh when they are alone. Under conditions which in 

 the presence of others would cause them to laugh they only 

 " chuckle " or smile, and may, though ready to burst into 

 laughter, not even exhibit its minor expressions when alone. 

 On the other hand, some sane people have the habit of 

 laughing aloud when alone, and there is a recognised form 

 of idiocy which is accompanied by incessant laughter, 

 ceasing only with sleep. Then there is that peculiar con- 

 dition of laughter which is called" giggling," which is laughter 

 asserting itself in spite of efforts made to restrain it, and 

 frequently only because the occasion is one when the 

 " giggl er " is especially anxious not to laugh. This kind 

 of "inverted suggestion," as in the case where an individual 

 " blurts out " the very word or phrase which he is anxious 

 not to use, is obviously not primitive, but connected with 

 the long training and drilling of mankind into approved 

 " behaviour " by" taboos "and restrictive injunctions. Efforts 

 to behave correctly, by causing anxiety and mental dis- 

 turbance in excitable or so-called " nervous " subjects, lead 

 to an overmastering impulse to do the very thing which 

 must not be done ! 



It seems that laughter has its origin far back in the 

 animal ancestry of man, and is essentially an expression 

 to others of the joy and exhilaration felt by the laugher. 

 It is an appeal through the eye and ear for sympathy and 

 comradeship in enjoyment. Its use to social animals is in 

 the binding together of the members of a group or society 

 in common feeling and action. Many monkeys laugh, 

 some of them grinning so as to show the teeth, partly 

 opening the mouth and making sounds by spasmodic 

 breathing, identical with those made by man. I have seen 

 and heard the chimpanzees at the Zoological Gardens 

 laugh like children at the approach of their friend and my 

 friend, the distinguished naturalist Mr. George Boulenger, 



