Structural Peculiarities and Behavior 55 



to that of the common mouse, but simply because I failed 

 to find any reliable description of the latter with drawings 

 which could be reproduced. The rabbit's ear, however, is 

 sufficiently like that of the mouse to make it perfectly satis- 

 factory for our present purpose. 



This drawing of the rabbit's ear represents the three semi- 

 circular canals, which occur in the ear of all mammals, and 

 which are called, by reason of their positions, the anterior 

 vertical, the posterior vertical, and the horizontal. Each 

 of these membranous canals possesses at one end, in an 

 enlargement called the ampulla, a group of sense cells. In 

 Figure 7 the ampullae of the three canals are marked respec- 

 tively, ampulla anterior, ampulla posterior, and ampulla 

 externa. This figure shows also the cochlea, marked lagena, 

 in which the organ of hearing of mammals (the organ of 

 Corti) is located. The ear sac, of which the chief divisions 

 are the utriculus and the sacculus, with which the canals 

 communicate, is not shown well in this drawing. 



Within a few months after the publication of Rawitz's 

 first paper on the structure of the dancer's ear, another 

 European investigator, Panse (23 and 24) published a short 

 paper in which he claimed that previous to the appearance 

 of Rawitz's paper he had sectioned and mounted ears of the 

 common white mouse and the dancing mouse side by side, 

 and, as the result of careful comparison, found such slight 

 differences in structure that he considered them unworthy 

 of mention. Panse, therefore, directly contradicts the state- 

 ments made by Rawitz. In fact, he goes so far as to say that 

 he found even greater differences between the ears of different 

 white mice than between them and the ears of the dancer 

 (23 p. 140). 



In a somewhat later paper Panse (24 p. 498) expresses his 

 belief that, since there are no peculiarities in the general form, 



