STRUCTURE OF THE WALL OF THE LABYRINTH. {$ 



they simply extend in a mechanical way the epithelial cells 

 originally situated at regular and definite distances from each 

 other, which Eberth has shown must be admitted to occur also 

 in many of the separable forms of epithelium lining various 

 vessels, and which holds equally for the vesicles of the lungs, 

 if it be true that they are lined by epithelium in the adult. 

 Although individual peculiarities occur in regard to the papillae, 

 I have never missed them entirely. At some distance from the 

 thin part of the wall, i.e., the part corresponding to the attach- 

 ment of the canal ligaments, they are never absent ; but on the 

 free side of the canal they are sometimes but feebly developed. 

 They are not found in the sacculus or near the openings of the 

 semicircular canals into the utriculus. I have on several occa- 

 sions seen isolated papillae near the dilated orifice of the mem- 

 branous horizontal canal. 



These structures, peculiar to the adult Man, have been re- 

 garded as pathological products (Voltolini, Lucae). Lucae has 

 stated in favour of his view that they are not present in the 

 newly born child ; that they have no epithelium ; and that, 

 owing to the reaction with iodine, they may be placed in the 

 same category as the amyloid corpuscles. On the other hand, 

 putting aside the first point as irrelevant, it may be observed 

 (1) that the papillae in the semicircular canals of adults, though 

 presenting individual variations in regard to the degree of their 

 development, were never found by me to be absent ; * and (2) 

 that by means of reagents the epithelium can be demonstrated, 

 whilst the well-known iodine reaction is common to them with 

 the tunica propria and many other tissues in which starch 

 proper still remains to be discovered. The rounded form which 

 the papillae assume under manipulation cannot certainly be 

 advanced as an argument in favour of their amylaceous charac- 

 ter. I have convinced myself, by making very fine transverse 

 sections of the membranous semicircular canals, that the papillae 



* If thirty subjects be taken successively from the dissecting room, 

 without reference to the nature of the previous disease, and an exami- 

 nation be made of their semicircular canals, the papillif orm processes will 

 be found in twenty-eight ; a numerical proportion which, independently 

 of other grounds, is, per se, sufficient to lead us to discard the idea of 

 their being pathological. 



H 2 



