414 SPECIAL HISTOLOGY. 



[In the description of the cochlea, I have altogether followed 

 Corti, having formerly satisfied myself of the correctness of 

 his statements, when that zealous and intelligent observer pur- 

 sued his investigations in Wurzburg j 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 habenula 

 denticulata, which are so difficult of investigation, have always 

 appeared to me to demand further consideration, and particu- 

 larly 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 ascertained, 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 (via 1 . Harless, 1. c.) . As 

 regards the nature of the so-termed "teeth," they are cer- 

 tainly, 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 epithe- 

 lium-cells (Corti) on the habenula denticulata are really epi- 

 thelial, as Corti supposes, still demands investigation. These 

 bodies, notwithstanding their great delicacy, appear to me rather 

 to be referable to the category of the other tissues of the ha- 

 benula 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, per- 

 fectly 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 desirable 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 with 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 



