LESSON 51.] NUTRITION IN THE MAMMALIA. 181 



table feeding animals ; thus, in the Sheep, the canal is upwards of 

 thirty times the length of the body, and it is of proportionate dimen- 

 sions in the Cow, &c. 



787. In structure, the intestinal canal presents a villous mem- 

 brane of great beauty, and the glandular system of the intes- 

 tines, so well displayed in the Carnivora and in man, is no less 

 displayed in these animals. 



788. In the small intestines, especially in the Ileum, patches of 

 glands more than a finger long present themselves ; these are the 

 glandulas aggregatse, or agmenatse (aggregated glands) of Peyer. 

 Usually these glands are non-vascular, but, in the figure of them 



FIG. 286. FIG. 287. 



Ileum and Peyer's glands, Calf. Colon, Calf. 



presented, drawn from a preparation (Fig. 286), it will be seen that 

 the surface of each gland (5, b) is covered with a network of capil- 

 laries, having wide meshes ; the villi (a, a), in the midst of which 

 the glands are situated, are beautifully seen. 



789. In all the higher animals it happens that the large intestine 

 (Colon) reproduces, as it were, the peculiar cellular structure which 

 distinguishes the stomach, and so very like it, that frequently it be- 

 comes very difficult, if not impossible, to discriminate between sto- 

 mach and colon ; this is the more surprising when we consider how 

 many yards of a totally different structure intervene between these 

 two organs. A figure of the Colon of a Calf is given (Fig. 287), in 

 which the cellular structure is shown. 



790. In the Carnivorous animals the structure of the teeth is es- 

 sentially different from those of the herbivora, and better adapted as 

 organs of prehension, mastication, and for tearing and dividing their 

 food ; but there is yet another organ singularly modified to suit spe- 

 cial wants, and this is the Tongue. 



791. The tongues of all the higher, and many of the lower verte- 

 brata, possess (usually) three forms of papillse-: the filiform (a thread 



