THE DIGESTIVE ORGANS. 51 



absorption is, however, effected chiefly in the intestines, with the 

 assistance also of the bile and pancreatic juice. But the pre- 

 paration of the food for absorption is not by any means completed 

 in this first part of the alimentary canal ; it is still to be submitted 

 to the action of various fluids as it passes on through the long 

 course of the intestines, which vary considerably in length in the 

 higher animals. In the carnivora, living on food easily digested, 

 the intestine is short, not being more than three times the length 

 of the body, whilst in the sheep it is twenty-eight times as long. 

 Again, in the omnivorous animals, as, for instance, man, the 

 length is from five to six times that of his body, being interme- 

 diate between the two. The mucous membrane of the alimentary 

 canal is everywhere studded with minute glands, which force out a 

 fluid varying according to the particular part in which they are 

 situated ; but, in all parts, there are some which secrete mucus, that 

 jelly-like fluid, a familiar specimen of which the lining membrane 

 of our own noses compels us to take notice of, and to store in our 

 pocket-handkerchiefs. In the stomach these glands principally 

 secrete gastric juice a strong solvent of animal and vegetable 

 food. The whole surface of the mucous membrane is covered with 

 what are called villi, and which resemble to the naked eye the 

 pile of velvet. In these the proper absorbent vessels originate, 

 and through them the prepared food is taken up and carried into 

 a duct (the thoracic duct), which finally empties itself in one of 

 the large veins near the heart. The food thus prepared by the 

 action of the saliva and the gastric juice in the stomach is called 

 chyme, and is then, after losing some small portions of its most 



E 2 



