PROPORTIONS OF THE TECTORIAL MEMBRANE 35 



procedure used by Held for his sections of the cochleae of the 

 rabbit. In so far as possible, I judge my preparations were no 

 more shrunken than were his. Judged from measurements and 

 the appearance of the teased out membrane, I am quite sure 

 they were not swollen. I have not studied the tectorial mem- 

 brane of the rabbit. He frequently referred to the tectorial 

 membrane of the adult rabbit but, unfortunately, does not figure 

 it. His figure 17, six days after birth, is the oldest stage he 

 exhibits in the rabbit. The rabbit being one of the rodents in 

 which parturition is comparatively premature, his six day old 

 rabbit was scarcely more developed in than a pig fetus about term. 



ON THE DEVELOPMENT AND ATTACHMENT OF THE TECTORIAL 



MEMBRANE 



The essential steps in the development of the spiral organ and 

 its tectorial membrane were worked out by Corti himself in 1851 

 and by Kolliker in 1861. Many other papers have dealt with 

 phases of the process, repeating and adding to the findings of 

 Corti and Kolliker, the most recent being those of Held and 

 Prentiss. Permission is asked here merely to review the process 

 as to its bearing upon two points: the position which the tec- 

 torial membrane acquires in its maturel}^ functioning condi- 

 tion and the attachment it retains. As indicated in my pre- 

 vious paper, both these points have been touched upon re- 

 peatedly without agreement in results. The most recent papers 

 fail to agree upon them. I have here tried to contribute quan- 

 titatively something as to the growth changes in the width of 

 the membrane, and as to the growth changes resulting in its 

 adult position with reference to the cells of the spiral organ and 

 also resulting in the one attachment it retains in the hog. 



In the hog, the length of the fetus is but an approximate cri- 

 terion of the stage of the development of its cochlea. Fetuses 

 obtained in California, for example, I have found average longer 

 at a given stage of the spiral organ than do fetuses from hogs 

 raised in Louisiana. The hog brought to the slaughter-house 

 averages larger in San Francisco than in New Orleans, due no 

 doubt to differences in breed and feeding, for very probably 



