GROWTH OF THE INNER EAR OF ALBINO RAT 



45 



of their closer zoological relationship, the rat and the rabbit are 

 in better agreement, although the rabbit appears to be a trifle 

 more advanced at birth than the rat. 



Finally, in the comparison of different series of data, differ- 

 ences due to the lack of homogeneity in the series of animals 

 used and to the various techniques employed can hardly fail to 

 play an important part, and allowance must be made for these 

 disturbing factors. 



When we consider the rate of growth, the ratio of a one to a 

 fourteen-day-old rabbit is 1:1.6, according to Retzius; therefore, 



TABLE 13 

 Breadth of basilar membrane 



it has very nearly the value found in the albino. In the cat, 

 however, the ratio between one and thirty days is 1:0.97; there- 

 fore, it apparently decreases a bit. 



This difference is most readily explained as due to the 

 precocious development in the cat at birth. 



On comparing the radial breadth of the membrane obtained 

 from several mammals by various authors, we find the following 

 values (table 13). 



The values here given must be read in the light of the various 

 modifying conditions to which reference has just been made. 



