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, 



ANIMAL 

 AUTHOR 



Man-New-born 



Hensen ('63) 



Man — Mature 



Retzius ('84) 



Calf 



Kolmer ('07) 



Pig 



Kolmer ('07) 



Goat 



Kolmer ('07) 



Cat 



Bottcher ('69) 



Cat 



Middendorp ('67) 



TABLE 13 



Breadth of basilar membrane 



TURN IN WHICH MEASUREMENT WAS MADE IN H 



Basal 



235 

 210 

 200 

 168 

 124 

 90 



Second 



413 



280 

 200 

 384 



Third 



340 



256 

 432 

 435 



Fourth 



495 

 360 

 400 

 304 



Average 



381 

 303 

 293 

 232 

 313 

 263 

 246-275 



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. 



