120 Irving Hardesty 



imperfecth- fixed will often show the membrane with no sign of lique- 

 faction when the cells of the organ are badly deranged. 



It was thought that the matrix might probably have a mucous char- 

 acter from the fact that preparations are occasionally seen in which 

 the membrane stains more or less deeply blue. To test this, specimens 

 w^ere appropriately fixed, prepared into sections and stained with 

 Meyer's muchasmatin and mucicarmine according to the procedure 

 followed by Bensley in his study of the glands of Brunner, but in 

 no case did the matrix take the stain in the way considered differential 

 for mucus. It was further found that the membrane never stains 

 deeply blue with hsematoxylin in preparations that have been carefully 

 washed after fixing and decalcification. Orcein and Weigert's stain 

 for elastic tissue likewise gave negative results. The matrix may be 

 somewhat similar to that of certain cartil'ages only much softer, or, 

 since studies of the development show the membrane to be a cuticular 

 structure, and since it is derived from cells of octodermal origin, the 

 matrix ma}^ be a variety of soft keratin. 



The Shape and Dimensions of the Tectorial Membrane. 



The cochlea of the pig is of the flat type. Gray, '07, has recently 

 divided cochleae into two general types, the sharp pointed and the flat. 

 The flat type is most common, being possessed by several varieties of 

 mammals, including the primates and ungulata, to which latter the pig 

 belongs, while the sharp pointed type is possessed by the carnivora and 

 rodents, the Edentata having an intermediate type and the Marsupials 

 both types. 



The pig has one turn more in the coil of its cochlea than in that of 

 the human ear. While the human cochlea is usually described as 

 having 2y2 turns, Wiedersheim, '93, accredits it wdth nearly 3 turns, 

 giving the pig 4 turns, the cat 3 turns, the rabbit 2l^, the ox 314, and 

 the cetacea II/2 turns. 



The tectorial membrane of the pig extends throughout the entire 

 length of the ductus cochlearis (scala media), and thus it is about as 

 long as the scala vestibuli, but not quite as long as the scala tympani. 

 Therefore, it is not quite as long as the basal side of the membranous 

 labyrinth. This relative extent is probably true for all the mammals. 

 Dupuis, '94, who studied teased preparations after fixation with osmic 

 acid, ]\Iuller's fluid, etc., and decalcification with hydrochloric acid. 



