588 BLOODVESSELS OF THE ALIMENTARY CANAL, BY C. TOLDT. 



the papillae. From this point the small veins, characterised 

 by their large lumen and straight course, receiving lateral 

 branches, and occupying the axes of the papillae, run towards 

 the centre of their bases, and descend perpendicularly to the ve- 

 nous plexus of the mucous membrane. This course enables them 

 to be easily distinguished from the capillary arterioles which run 

 obliquely towards the papillae. As we recede from the margin 

 of the lips, the vascular arrangement of the papillae assumes a 

 more simple character, so that in those of the posterior surface 

 of the lips the capillary loops are either simple, or have only 

 one or two transverse branches. The papillae of the cheeks, 

 in like manner, have only simple capillary loops. 



The papillae of the hard palate are of considerable height 

 anteriorly, yet, for the most part, contain only a single vertical 

 vascular loop; posteriorly, the height of the loops is much 

 diminished, and on the soft palate they form only flat arches, 

 which, originating in the relatively close-meshed plexus of 

 the mucous membrane, present the convexity of their arches to 

 the surface. 



The gums bear papillae on their free surface, the vascular 

 plexus of which is nearly as much developed as in those of the 

 lips, but in those of the lateral surfaces there is only a single 

 capillary loop. 



The papillae on the floor of the mouth have single loops, with 

 occasionally one or two cross branches. 



Langer * has very recently called attention to a remarkable 

 arrangement that is found in the frog. In this animal the 

 capillary vessels of the mucous membrane of the mouth and of 

 the oesophagus as far as the cardiac orifice of the stomach pre- 

 sent numerous diverticula, which project towards the free sur- 

 face of the membrane, and, after becoming constricted, terminate 

 in the capillary vessels. Langer is no doubt justified in re- 

 garding these as a peculiar arrangement supplying the place of 

 capillary loops, and adduces, in support of his opinion, the fact 

 that in the toad these diverticula are replaced by the ordinary 



* Sitzungsberichte der k. k. Akademie der Wissenschaften zu Wien, 

 Band lv., Abtheil 1 ; Ueber das Lymphgef assy stem des Frosches, " On the 

 Lymphatic System of the Frog." 



