THE DEVELOPMENT OF THE HUMAN SKULL. 161 



him regarding the origin of the stapes. According to this 



writer : — " The middle division of the cartilaginous axis applies 

 itself to the vesicular cartilaginous labyrinth, and when it comes 

 into contact with the labyrinth, it sends out a small nodule, 

 which is received by a pit, the future fenestra ovalis." The 

 nodule grows out into a process, the lower part of which be- 

 coming bent on the upper, and eventually articulated, is con- 

 verted into the stapes, while from the upper part originates the 

 long process of the incus. 



The auditory ossicles are at first altogether outside the 

 tympanic cavity ; and as the latter enlarges, its mucous mem- 

 brane is reflected around the ossicles. The deposit of osseous 

 matter for each ossicle commences in the perichondrium, and 

 the stapes has three ossific centres, independently of that for the 

 os oroiculare. 



It can hardly be doubted that there is much yet to be 

 learned respecting the first steps in the development of the 

 ossicula auditus ; but the investigation is one fraught with 

 difficulties.* 



* See Magitot et Robin, " Cartilage de Meckel." Ann. des Sc. Nat. Se. IV C . 

 tome xviii. 



M 



