: 



DiGK ON.] PHYSIOLOGY, ill 



cells, and wrapped round with blood capillaries. From 

 these capillaries, a watery fluid passes into the tubes, 

 and from the tubes into thq alimentary canal. This 

 watery fluid is, however, of a difl*erent nature from 

 sweat, and is not the same in all parts of the canal. 

 The fluid which is, as we say, secreted by the glands 

 in the walls of the stomach is an acid fluid, and is 

 called gastric juice ; that by the glands in the walls 

 of he intestines is an alkaline fluid, and is called 

 iii;Ustinal juice. 



48. But besides these glands in the mucous mem- 

 brane of the mouth, the stomach, and the intestines, 

 there are other glands, which seem at first sight to 

 have nothing to do with the mucous membrane. 



Beneath the skin, underneath each ear, just be- 

 hind the jaw, is a soft body, which ordinarily you 

 cannot feel, but which, when inflamed by what is 

 called "the mumps," swells up into a great lump. 

 In a sheep's head you would find just the s^,me 

 body, and if you were to examine it you would 

 notice fastened to it a fleshy cord running underneath 

 the skin across the cheek towards the mouth. By 

 cutting the cord across you would discover that what 

 seemed a cord was in reality a narrow tube coming 

 from the soft body we are speakhig of and opening 

 into the mouth. Just close to the soft body this tube 

 divides into two smaller tubes, these divide again into 

 still smaller ones, or give off small branches ; all these 

 once more divide and branch like the boughs of a tiity 

 tree ; and so they go on branching and dividing, getting 

 smaller and smaller, until they end in fine tubes with 

 blind swollen ends. All the tubes, great and small, 

 are lined with epithelium and wrapped round with 



