8o The Dancing Mouse 



what looked like a response to some sound appeared, but 

 critical observation invariably proved it to be due to some 

 other cause than the auditory stimulus. A sound produced 

 above the animal is very likely to bring about a motor re- 

 action, as Cyon claims ; but I have always found it to be the 

 result of the currents of air or odors, which usually influence 

 the animal when the experimenter is holding any object above 

 it. I do not wish to maintain that Cyon's conclusions are 

 false; I merely emphasize the necessity for care in the 

 exclusion of other stimuli. The mice are extremely sensitive 

 to changes in temperature, such, for example, as are produced 

 by the breath of the experimenter, and one must constantly 

 guard against the misinterpretation of behavior. 



In a single experiment with mice over a month old, I 

 observed what might possibly indicate sensitiveness to sound. 

 While holding a mouse, thirty-five days old, in my hand I 

 pursed, my lips and made a very shrill sound by drawing in 

 air; the mouse seemed to start perceptibly according to the 

 indications given by my sense of touch. I repeated the 

 stimulus several times and each time I could see and feel the 

 animal start slightly. With two other individuals which I 

 tested the reaction was less certain, and with several others 

 I failed to get any indication of response. This would seem 

 to prove that the three individuals which responded happened 

 to be sensitive to that particular tone at the age of five weeks. 

 The test is unsatisfactory because the vibrations from my 

 own body may have brought about the reaction instead of 

 the air vibrations produced by my lips, and I therefore merely 

 mention it in the enumeration of the various experimental 

 tests which I have made. 



If we should conclude from all the negative evidence that 

 is available, or that could be obtained, that the dancer is 

 totally deaf, it might fairly be objected that the conclusion 



