64 THE SPEECH OF MONKEYS. 



peculiar clucking sound. Many of these tests 

 I have repeated over and over with the same re- 

 sults, and noting the conditions at the time, I am 

 thoroughly convinced that the sign and sound 

 mean "no." I have observed that this sign is 

 always made in the same manner ; but sometimes 

 it is accompanied by a clucking sound, while at 

 other times it is a soft, whimpering sound, al- 

 most like a low, plaintive whistle. The sign is 

 frequently used without the sound at all ; and I 

 must impress it upon my reader that these re- 

 sults do not always present themselves in every 

 experiment, as much depends upon the mood 

 and surroundings of the subject. I have found 

 that one advantage is to have the monkey con- 

 fined in a very small cage, as otherwise he will 

 turn away and get out of your reach when you 

 press anything upon him that he does not want. 

 I have also found much better results by having 

 the monkey alone, and where he can neither see 

 nor hear other monkeys. 



Having discovered the sign of negation among 

 the simians, I began an investigation to ascer- 

 tain how far it could be found among the races 

 of mankind. I have carried my search far be- 

 yond the limits of local inquiry, and up to this 



