THE SALIVARY GLANDS. 949 



.<) that there is hardly any lumen perceptible. Instead of presenting the clear, 

 transparent appearance of the cells of the mucous alveoli, they present a granular 

 appearance, due to distinct granules of an albuminous nature imbedded in a closely- 

 reticulated protoplasm. The ducts which originate out of the alveoli are lined at 

 their commencement by epithelium which differs little from the pavement type. 

 A- the ducts enlarge the epithelial cells change to the columnar type, and they are 

 described by Pfiiiger as attached to the basement membrane by a brush of fine 

 hair-like processes, which he believes to be continuous with the nerve-fibres. 

 Other anatomists regard these cells as merely striated on their deep surface. 

 The lobules of the salivary glands are richly supplied with blood-vessels which 

 form a dense network in the interalveolar spaces. Fine plexuses of nerves are 

 als' found in the interlobular tissue. 

 Pfluger describes the nerves as being 

 directly continuous with the salivary 

 cells of the alveolus, the nerve some- 



FIG. 571. Illustrating Pfluger s views of the termination of the nerves in the alveolar cells. (From Strieker's 

 Handbook.") A. Direct passage of nerve into a salivary cell. B. By the medium of a multipolar ganglion-cell, g. 



times passing through a ganglion-cell just before joining the alveolus (Fig. 571, 

 A and B). This fact has not. however, been corroborated by other observers. 

 There is no doubt that ganglia are to be found in some salivary glands in connec- 

 tion with the nerve-plexuses in the interlobular tissue; thus they are to be 

 found in the submaxillary. but not in the parotid, but whether the ultimate 

 fibrils are connected with the salivary cells, as asserted by Pfluger, remains to be 

 proved 



In the submaxillary and sublingual glands the lobes are larger and more 

 loosely united than in the parotid. 



Jftfcotu Glands. Besides the salivary glands proper, numerous other glands 

 are found in the mouth. They appear to secrete mucus only, which serves to keep 

 the mouth moist during the intervals of the salivary secretion, and which is mixed 

 Avith that secretion in swallowing. Many of these glands are found at the posterior 

 part of the dorsum of the tongue, behind the circumvallate papillae, and also along 

 its margins as far forward as the apex. 1 Others lie around and in the tonsil 

 between its crypts, and a large number in the soft palate. These glands are of 

 the ordinary compound racemose type. 



Surface Form. The orifice of the mouth is bounded by the lips, two thick, fleshy folds 

 covered externally by integument and internally by mucous membrane, and consisting of 

 muscles, vessels, nerves, areolar tissue, and numerous small glands. The size of the orifice of 

 the mouth varies considerably in different individuals, but seems to bear a close relation to the 

 size and prominence of the teeth. Its corners correspond pretty accurately to the outer border 

 of the canine teeth. In the Mongolian tribes, where the front teeth are large and inclined for- 

 ward, the mouth is large ; and this ; combined with the thick and everted lips which appear to 

 be associated with prominent teeth, gives to the negro's face much of the peculiarity by which 

 it is characterized. The smaller teeth and the slighter prominence of the alveolar arch of the 



1 It has recently been shown by Ebner that many of these glands open into the trenches around 

 the circumvallate papillae, and that their secretion is more watery than that of ordinary mucous 

 glands. He supposes that they assist in the more rapid distribution of the substance to be tasted over 

 the region where the special apparatus of the sense of taste is situated. 



