DIGESTION 01 



of the alimentary canal and get into the blood, and by the 

 blood be distributed to all the cells of the body. 



There are a number of glands opening into the alimentary 

 canal; the salivary glands, which produce saliva, open into 

 the mouth; then there are innumerable glands packed close 

 together in the walls of the stomach, which secrete the 

 gastric juices. Then we have the liver and pancreas. The 

 saliva passing into the stomach turns starch into sugar before 

 the action of the gastric juice has rendered the stomach- 

 contents acid. But saliva also helps to moisten the food and 

 thus to make it more easy to swallow. When the Red Queen 

 in Alice Through the Looking-Glass after their tremendous 

 race offered the dry-mouthed and tired-out little girl a 

 dry biscuit, one can well imagine that Alice had difficulty in 

 swallowing it. 



The gastric juice in the stomach dissolves up proteins and 

 makes of them a solution which can pass through the mem- 

 brane of the intestine. The bile which comes away from the 

 liver, and also the pancreatic juice, break up the fat into the 

 minute particles such as can be seen if milk be examined 

 under the microscope. In technical terms they emulsify it. 

 It is then capable of passing through the membrane which 

 forms the coat of the intestine. But the emulsified fat, 

 now termed chyle, does not pass into the blood directly. In 

 the first place it passes into some small vessels called lacteals, 

 and these lacteals are always filled with the milk-like solution 

 of fats. Ultimately they combine into larger and larger 

 vessels, and the largest of these pours the chyle into one 

 of the great veins near the neck, so that in time the fat docs 

 get into the blood, and thence to all the tissues and cells 

 that want it. Pancreatic fluid also helps in changing starch 

 into sugar. Water passes into the blood along the whole course 

 of the alimentary canal, and with it the dissolved minerals, 

 so that all real foodstuffs ultimately pass either straight into 

 the blood or through the lacteals into the blood, leaving 

 behind in the intestine the undigested insoluble parts to be 

 cast out of the body. 



The blood^n higher animals — transports the digested 

 food throughout all the tissues and in such a form as to supi)ly 



