38 THE EXTERNAL AND MIDDLE EAll, BY J. KESSEL. 



ossification of the periosteum at the point of fusion. About 

 this time also the connection of the malleus with the membrana 

 tympani is very intimate, though only at two points ; namely, 

 at the processus brevis, where the ligaments extending from the 

 borders of the Rivinian gap are inserted into it, and at the 

 lower third of the manubrium, where a portion of the radial 

 fibres give additional strength to the periosteum, whilst the 

 others decussate in front of the manubrium, in order to become 

 continuous with the irregular layer found between the radial and 

 circular fibres. The membrana propria is only connected with 

 the periosteum of the upper part of the manubrium by means 

 of loose connective tissue, so that a slight capability of move- 

 ment exists at this part also, without any kind of articulation 

 being present. The mucous membrane as it passes from the 

 inner surface of the membrana tympani to the malleus is 

 scarcely perceptible at its attachment to the former. 



The statement that the tympanic cavities are filled throughout the 

 whole of intra-uterine life with young connective tissue requires corro- 

 boration, as I have frequently found them filled with fluid in old 

 embryoes and new-born children, their mucous membrane being at the 

 same time coated with epithelium. 



The mucous membrane of the membrana tympani is composed 

 of an epithelium resting on a fibrous matrix. The epithelium 

 which has hitherto been described as consisting of a simple 

 layer of pavement epithelium, by no means presents this cha- 

 racter throughout, but has the same peculiarities of form as 

 that described by Ludwig and Schweigger-Seidel (48) in the 

 epithelium of the abdominal surface of the diaphragm in the 

 Rabbit. After treatment with nitrate of silver, polygonal areas 

 of various size, enclosed by dark sinuous lines, come into view 

 on the surface of the mucous membrane, as is seen in fig. 280. 

 Where these lines meet, more or less round or angular spots 

 appear (d) which give the impression of openings, an impres- 

 sion that is strengthened by the circumstance that they appear 

 to be homogeneous after treatment with iodine-serum. The 

 polygons may be distinguished as large (a), small (6), and 

 smallest (c) ; the latter lying in particular along the manubrium 

 and towards the periphery, and enclosing the most homogeneous 



