THE EAR. 355 



cartilage, in which the handle of the hammer lies, kept in place 

 by the mucous layer which passes over and is firmly adherent 

 to it ; the upper part of this furrow ends in a sort of cartilagi- 

 nous cap, into which the processus brevis fits.) Transverse 

 sections made after hardening the membrane in Miiller's fluid 

 and alcohol, and then imbedding, give the best idea of these 

 relations. 



The inner or mucous layer is formed of flat epithelium, sup- 

 ported on a reticulated layer of connective tissue, and directly 

 continuous with the epithelial lining of the middle ear. The 

 arterial supply is furnished by a small arteriole, which follows 

 the handle of the malleolus, and gives off lateral capillaries 

 anastomosing with others coming from small branches which 

 enter at the periphery. The blood is collected into venous 

 trunks which pass out in a similar manner. Fine nerves are 

 said to be found in close connection with the vessels. They 

 apparently come from the sympathetic system. 



The middle ear. In order to obtain a clear idea of the rela- 

 tions and structure of the middle ear a fresh temporal bone, 

 with the soft parts still adherent, must be decalcified by soak- 

 ing for a long time in a per cent, solution of chromic acid, 

 which should be frequently changed ; it is then to be washed 

 in distilled water for twenty-four hours, and hardened in alco- 

 hol, when it will be ready for cutting. 



A section from a specimen thus prepared shows that the 

 whole middle ear is lined by a layer of pavement-epithelium, 

 supported upon two layers of connective tissue, one serving as 

 a submucous layer and the other as a periosteum. This tis- 

 sue is thrown into ridges corresponding to the bony promi- 

 nences, in the hollows of which, the vessels and nerves lie. Ac- 

 cording to Kessel the submucous layer is provided with, oval 

 expansions, recalling the Pacinian bodies found in the mesen- 

 tery of the cat. The existence of muciparous glands in the 

 human tympanum has yet to be confirmed. A plexus of nerves 

 is described as distributed in the subepithelial tissue, in the 

 nodal points of which are found scattered ganglion-cells. The 

 lining of the tympanum passes directly into that of the mastoid 

 cells, and has there the same general arrangement. 



The Eustachian tube. In direct communication with the 

 tympanum stands the Eustachian tube, composed like the ex- 

 ternal ear of a cartilaginous and an osseous portion. The car- 



