44 



ANATOMICAL AND PHYSIOLOGICAL STUDIES ON 



Comparing these values with mine obtained for the albino 

 rat, it is to be noted that those of Retzius are generally larger 

 than those for the albino. For example, while I get at birth 

 only 126 (x in the basal turn, Retzius ('84) obtains 180 [x in the 

 rabbit and even 270 [x in the cat. As stated above, the radial 

 breadth increases in the albino rat continuously with age. It 

 is very peculiar to find in the Retzius table that the breadth 

 of the membrane in the cat is decidedly larger at birth than at 

 three and seven days. The average value for the new-born is 

 315 [x, which is larger than at thirty days, which is 310 [x. 



Retzius ' data show the membrane in the rabbit and cat always 

 wider in the apical than in the basal turn at birth and at two 



TABLE 12 

 Breadth of membrana basilaris according to turns, p. (From Retzius, '84} 



days. My results, given in table 10, show the reverse at the 

 ages of one and three days. This is an expression of greater 

 immaturity in the case of the rat. 



In comparisons like the foregoing, several conditions must 

 be kept constantly in view. 



So far as absolute values are concerned, it is to be expected 

 that these would be unlike in the different mammals, because 

 the cochleas differ in size. As to the relations between the values 

 at birth and at maturity, it is plain that these cannot be ex- 

 pected to agree unless the cochleas of the animals compared 

 are in the same phase of development at birth. In the foregoing 

 instances it appears that the cat is relatively precocious, as 

 compared with the rabbit, while, as might be expected, because 



