THE EAK. 777 



histological development of tbe soft parts of the labyrinth, nothing of 

 consequence is known. 



In the description of the cocJilea, I have altogether followed Corti, 

 having formerly satisfied myself of the correctness of his statements, 

 when that zealous and intelligent observer pursued his investigations in 

 Wurzburg ; and having also, recently, confirmed the greater part of 

 them by the examination of the human cochlea. At the same time the 

 parts of the hcibenula dcnticulata, which are so difiicult of investigation, 

 have always appeared to me to demand further consideration, and par- 

 ticularly with respect to the ascertaining of the kind and mode of the 

 movements of its processes, the relations of the epithelium, and of the 

 investing, structureless membrane. So long as these points are not as- 

 certained, all suppositions respecting the function of these delicate 

 structures are without any secure basis, and the physiology of the 

 cochlea, otherwise so difficult, is rendered only still more perplexed 

 [vid. Harless, 1. c). As regards the nature of the so-termed '' teeth," 

 they are certainly, as Corti assumes, nothing more than developments 

 of the periosteum of the cochlear canal, and may, in my opinion, 

 although in chemical respects very similar to the vitreous membranes, 

 yet be regarded as belonging to the connective-tissue group. Whether 

 the three so-termed cylinder epithelium-cells (Corti) on the hahenida 

 denticidata are really epithelial, as Corti supposes, still demands inves- 

 tigation. These bodies, notwithstanding their great delicacy, appear 

 to me rather to be referable to the category of the other tissues of the 

 hahenida denticulata; and on that account I have termed them "teeth 

 of the third series."* 



For the investigation of this organ, which, however, presents any 

 very considerable difficulties only in the labyrinth, perfectly fresh objects 

 are indispensable, and are best taken from animals just killed. For the 

 moistening of them, serum or syrup should be employed, when it is de- 

 sirable to view the parts in a perfectly normal condition. Successful 

 results will be obtained, especially if a certain amount of practice, in 

 the exposing and dissection of the delicate tissues with which we have 

 to do, be combined Avith great patience, seeing that it is often a matter 

 of chance whether any given relations are brought into view. In order 

 to see the nervous plexus of the osseous zone of the cochlea, the latter 

 must be deprived of its calcareous constituents by dilute muriatic acid; 

 whilst in the case of the ganglion-cells in that situation, the only means 

 of attaining our object consists in a careful breaking down of the osseous 

 zone in a neutral medium. 



* {Vid. Note p. 775.— DaC] 



