74 THE EUSTACHIAN TUBE, BY PROFESSOR RUDINGER. 



bottom of the osseous portion of the tube, as I have already 

 elsewhere had an opportunity of describing, delicate folds ap- 

 pear of various height, which, when seen in transverse section, 

 present the form of villous processes. 



In the cartilaginous portion of the tube, the mucous mem- 

 Fig. 289. 



Fig. 289. Transverse section of the Eustachian tube of Man, in its 

 upper third. 1, Median cartilage ; 2, lateral cartilaginous hook ; 

 3, perichondrium ; 4, submucous layer ; 5 attachment of the dilatator 

 tubse ; 6, safety tube (Sicherheits-rohre) ; 7, lateral projection of 

 the mucous membrane ; 8, median projection of the mucous mem- 

 brane ; 9, accessory fissure (Hilfs-spalte). Magnified 184 diameters. 



brane and the cavity it encloses present many points of differ- 

 ence from that of the osseous portion, since in it acinous mucous 

 glands and peculiar foldings occur, which are intimately con- 

 nected with the mechanism of the tube. 



In the adult Man I have distinguished two divisions in the 

 tubal fissure. I have applied the term " safety tube " (Sicher- 



