424 THE DIGESTIVE APPARATUS IN MAMMALIA. 



provision for the parts which are removed from the direct contact of alimentary 

 matters — as, for example, on the lateral aspects of the tongue, where the buccal 

 membrane is delicately organized. 



This membrane also shows, in its lingual portion, small organs for the 

 perception of savours, which is one of the most important preparatory acts 

 of the digestive functions ; as the sensation resulting from this appreciation 

 constitutes an excitant to the desire for food, and also informs the animal of the 

 good or bad properties of the substances introduced into the mouth. 



Differential Characters in the Modth of the other Animals 

 That the diflfL-rent regions of the mouth in the domesticated animals should offer some 

 diversities, will be leadily conceived, as all are not submitted to the same regime, nor do they 

 all live in tlie same manner. 



Ruminants. 1. Lips.— The lips of the Ox are remarkably thick and rigid, and possessed 

 of little mobility, notwithstanding tlie great development of the muscles that move them; so 

 that they only concur indirectly in the prehension of food, the tongue being charged with the 

 largest share in this important task. The upper lip offers, in the middle of its external surface, 

 a large patch destitute of hair, variously coloured in different animals, always humid in health, 

 covered by small depressed eminences, and perforated by minute apertures, through which 

 tlie secretion of numerous thick, yellow, subcutaneous glandules passes to the surface. This 

 space, situated between the two nostrils, constitutes the muffle. (Around the muffle are some- 

 times a few hairs of the nature of tentaculse.) 



In the Camel, Sheep, and Goat, the lips are thin and very mobile, and take an active 

 part in the prehension of food. The upper lip does not show any muffle, and is divided into 

 two portions by a median groove. In the Camel and Sheep, this groove is in reality a fissure ; 

 80 that each half of the lip can be readily moved independently of the other. (The upper lip 

 Is covered with hair in these animals. The Goat has a long tuft of hair appended to its lower 

 lip, the beard.) 



2. Cheeks. — On the inner surface of the cheeks in the Ox, Camel, Sheep, and Goat, 

 from the commissure of the lips to the first molar tooth, is a multitude of long, thick, conical 

 papillsB directed backwards. Beyond, there are only small round elevations and a single row 

 of large papillae similar to the pn ceding, in a line with the upper molars. In the Sheep the 

 mucous membrane is sometimes spotted black ; in the Camel it is uniformly black. 



3. Palate. — In the Ox, the palate is most extensive. Its posterior third is quite smooth, 

 and the transverse ridges (bars) only occupy the anterior two-tiiirds. (They are usually 

 sixteen in number.) They are not curved, but are cut into notches on their summit, which 

 is inclined backwards. In the Sheep and Goat, as also in the Ox, is remarked, in front 

 and in the middle, near the pad that replaces the upper incisor teeth, a kind of T, the stem of 

 which is directed forwards, and at the extremity of its branches is a very narrow aperture, the 

 buccal opening of Jacobson's canal (see the Nasal Cavities for a description of this canal). 



On the palate of the Camel is a small salient crest that occupies the anterior two-thirds 

 of the middle line, and on each side are traces of transverse furrows, which are rather large 

 tubercles a little elongated from side to side. 



4. Tongue. — The tongue of the Ox is distinguished hy the enormous development of the 

 muscles composing it. It is garnished with conical papillae which have a horny sheath, and 

 their summits, inclining backwards, give the tongue a very rough feel. In this animal it 

 serves for the prehension of food ; its mobility is very great, and it can be carried into the 

 nostrils with ease. (The body of the organ is rounder, and the point finer, than in the Horse. 

 The calyciform papillae are spread over the whole of its dorsal surface ; and at the root, on the 

 middle line, is a somewhat deep groove.) 



The tongue of the Sheep, Camel, and Goat is smaller, proportionally, than that of 

 Solipeds. 



That of the Camel has an extremely rich papillary development. On the borders of the 

 upper surface of the free portion are about half a dozen calyciform papillae, more or less large, 

 but some of them have a greater diameter than Morgagni's foramen. On the posterior half of 

 the same part are foliated papillae, which are less numerous and smaller as they proceed back- 

 wards. On the sides are small perforated prolongations analogous to the barbs of Wharton's 

 ducts. 



5. Soft Palate. — It may be said, in a general manner, that the palatine prolongation is 

 shorter than in Solipeds. (The isthmus of the fauces is wider, however, and the amygdalae, 



