52 THE EXTEKNAL AND MIDDLE EAR, BY J. KESSEL. 



On moving the covering glass, the cell with the fibre floated 

 freely in the mounting fluid, so that it was impossible to enter- 

 tain any doubt of their connection. Riidinger also described 

 fibres in the mucous membrane of the tuba Eustachii, conti- 

 nuous on the one hand with the epithelial cells, and on the 

 other hand with the tissue of the submucosa. 



Besides these forms of columnar cells, there is another fusi- 

 form variety characterised by the nucleated body of the cell 

 becoming attenuated as it extends both upwards and down- 

 wards. The upper process extends to the epithelial margin ; 

 whilst the lower is columnar, with a bright highly refractile 

 fibre, which is lost in the subjacent tissue, and not unfrequently 

 presents a nodal enlargement near the cell from which it 

 proceeds. 



In regard to the pavement epithelium, it may here be ob- 

 served that wherever it occurs it presents the same peculiarities 

 of form as that which has been already described as covering 

 the mucous membrane of the membrana tympani. If the 

 epithelium be detached, and the mucous membrane be treated 

 by the silver method, serous canals come into view ; but if the 

 epithelium be not removed, and a solution of chloride of gold 

 or perosmic acid be poured over it, dark red or bla.k stellate 

 intercommunicating lines appear (with especial distinctness in 

 the Dog and Cat) immediately beneath the epithelium, which 

 are here and there continuous with broad and similarly dark- 

 coloured striae that are lost in the deeper layers of the tissue. 

 The question whether these last are to be regarded as identical 

 with those brought into view by nitrate of silver, and whether 

 like them they may be in intimate relation with the lymphatics, 

 must at present remain open, as I am unable to adduce any 

 positive evidence in favour of either view. 



Two layers can be distinguished in the subjacent stratum of 

 connective tissue, an upper lying immediately beneath the 

 epithelium, and a lower, which represents the periosteum, and 

 at the same time gives off fibres to the sheaths of the nerves 

 running in the grooves of the bone, as well as in the tunica 

 adventitia of the vessels of the bone. The upper layer forms 

 a fibrous framework, which is to be regarded as the prolonga- 

 tion of that I have more minutely described in the membrana 



