1 42 



THIRTEENTH LECTURE. 



Fig. 133. — Acini (a, round, 6, ob- 

 long) of a serous gland from the 

 vicinity of a circumvoluted papilla of 

 the cat. 



p. foliata, quite similarly shaped glands appear, it is true, but 

 they have different anomalous contents, with granular cloudy 



cells (Fig. 133). The same organs 

 have been met with in great numbers 

 in the nasal mucous membrane, and 

 they have received the name of the 

 " serous glands" (Heidenhain). 



The tissue of the mucous mem- 

 brane commences at the posterior 

 fourth of the tongue to undergo a 

 lymphoid metamorphosis, in which 

 the pharynx may also participate. 

 We thus have demarcated lymphoid 

 organs, the lingual follicles, the ton- 

 sils, and the pharyngeal tonsils, discovered by Koelliker 

 (compare p. 1 13). 



The pharynx, with its transversely striated muscles, has the 

 same covering of stratified pavement epithelium as the oral 

 cavity. The tough mucous membrane acquires papillae below. 

 The upper portion is rich in mucous glands. 



The oesophagus also retains the old epithelial covering. 

 The muscular coating consists of a thicker longitudinal ex- 

 ternal layer and a thinner internal transverse layer, and, as it 

 descends, shows a replacement of the voluntary transversely 

 striated fibrous formation by the involuntary smooth tissue. 

 The mucous membrane projects in longitudinal folds, and 

 contains racemose mucous glands. 



We may touch upon these only cursorily. 

 The stomach or ventriculus, on the contrary, requires a 

 more careful discussion. Its serous covering, it is true, pre- 

 sents nothing worthy of remark, neither do its smooth muscles, 

 which consist of layers running in longitudinal, transverse, 

 and oblique directions. But the mucous membrane, which is 

 lined with cylinder cells 0.0226 to 0.0323 mm. high and 0.0045 

 to 0.0056 mm. broad, shows, on the contrary, an abundance 

 of interesting and important things. 



Its surface is not smooth, but uneven. Either lower or 



