THE MUCOUS MEMBRANE OF THE EUSTACHIAN TUBE. 81 



and more gelatinous. F. E. Schulze has also described cup- 

 cells in the epithelium of the Eustachian tube, and on exa- 

 mining my finest sections with a view of discovering these 

 cells, I observe between the columnar cells, and situated at 

 definite distances from one another, moderately wide spaces, a 

 disposition that approximatively coincides with that described 

 and pictured as cup-cells. Subjacent to the epithelium and 

 the basement membrane is a fibrous layer, containing nume- 

 rous nuclei, and presenting different characters in the osseous 

 and cartilaginous tuba. The layer of connective tissue corre- 

 sponding to the cartilaginous portion of the Eustachian tube, 

 is developed inversely to the glandular layer; where the 

 glandular tissue is thick, as in the neighbourhood of the tubal 

 fissure, this fibrous layer is thin ; but where the glands are 

 entirely absent, as in the safety tube, the fibrous layer attains 

 its maximum. A dense layer of connective tissue of considerable 

 thickness makes its appearance above, in the bony tuba be- 

 neath the lateral portion of the cartilage, and here the tendinous 

 fibres of the musculus dilatator tubse are partially interwoven 

 with it. At this part, dense connective tissue is also present at 

 the bottom of the tubal fissure, partly produced by the tendi- 

 nous fibres of the levator palati muscle. It may be said that 

 the upper end of the Eustachian tube receives from this dense 

 tissue a compact investment in addition to the above-described 

 bone and rectangular plate of cartilage, on which the muscles 

 can exert but a very small influence. If the transverse section 

 be made somewhat lower down, a sharp line of demarcation 

 becomes apparent between the flat tendons of the dilatator 

 tubse and the submucous connective tissue, and still deeper is a 

 layer of fat. 



Mucous glands are entirely absent in the membrane of the 

 safety tube throughout the whole length of the Eustachian 

 tube. In the middle segment of the tubal fissure the acinous 

 glands form a distinct layer, becoming thicker inferiorly be- 

 tween the median cartilaginous lamella and the superimposed 

 mucous membrane. Gland vesicles also occur laterally between 

 the dilatator tubse and the epithelium, and extend at some 

 points as far as to the truncated extremity of the lateral car- 

 tilage. The mucous glands are similar in structure to those of 

 VOL. III. G 



