ORGANS OF THE BODY. 459 



the mouth. In this substance are to be found globular groups of fat 

 cells and the bodies of mucous glands. 



The last named organs (fig. 442) present themselves in large numbers 

 in the mucous membrane of the mouth. They measure in diameter from 

 4-5 and 2'3 down to 0*5640 mm., or even lower, and are usually situated 

 in a row underneath the true mucosa, where they may be so closely 



Fig. 441. Epithelial cells from Ftg. 442. Racemose mucous glands 



the most superficial layers of from man (so-called palatal glands), 



the mucous membrane of the 

 human mouth. 



crowded as to form a regular special glandular stratum. From this their 

 short and more or less straight ducts penetrate the mucous membrane, 

 and open on the surface. Their structure is as elsewhere : for which 

 see sections 198 and 197. 



In certain localities these little glands, which play an important part 

 in the production of the mucus of the mouth, are particularly numerous, 

 and then receive special names. Such are the labial, buccal, and palatal. 

 The first of these, which are very numerous, form, at some little distance 

 from the red margin of the lip, a regular group. They are most 

 numerous in the under lip (Klein). Their cells usually present them- 

 selves in the form of numerous low, clear, columnar elements, but slightly 

 coloured by carmine, as was very correctly described by Puky Akos. 

 According to Heidenhain, however, there occur also (in man and the rab- 

 bit) other smaller elements, richer in protoplasm, from the transformation 

 of which the first take their rise. The little palatal glands, likewise, are 

 arranged in a thick pad under the mucous membrane of the soft palate. 



The vascularity of the mucous membrane of the mouth is very great, 

 the capillaries forming a close network. In the papillae we encounter 

 either a single loop or congeries of vessels (fig. 440). We are still to a 

 great extent in the dark as to the lymphatics. So much is known, how- 

 ever, that they interlace along the lips, the inner surface of the cheeks 

 and the tongue, and covering the glands of the mouth, form interlace- 

 ments, which communicate with the vessels of adjacent parts (Teichmann). 

 The final distribution of the nerves of the mouth is a point on which 

 even less is known. Krause observed end-bulbs upon them ( 184), in 

 the furrows of the mucous membrane on the floor of the mouth, near the 

 tongue, in the soft palate, and in the tissue of the membrane, at the edge 

 of the red margin of the lips, but not always in the papillae. Elin states, 

 on the other hand, that both in the hard and soft palate of the rabbit, 

 fine nerve filaments penetrate into the epithelium, and ( 245) terminate 

 in ramifying cellular bodies ( 187). 



