176 



HITCHCOCK'S AJTATOMY 



highly alkaline character of the biliary secretion. Another 

 use of the bile is to remove certain materials from the blood 

 (the carbonaceous), by allowing them to pass off with the 

 waste portions of the food, the liver thus performing the office 

 of an excretory organ. The liver also seems to possess the 

 power of forming sugar and even fat, when it is not contained 

 in the food, thus seeming to act the part of an equilibrator in 

 the process of blood making. And since all the blood re- 

 turning from the small intestines passes through the liver 

 before going to the heart, without doubt an important change 

 is accomplished in it by the liver, although the change is as 

 yet by no means fully understood. 



321. Purposes for which Food is required. Two kinds 

 of Materials in the Food, azotised and non-azotised, 

 Azotised Constituents. Albumen, Fibrine, Casein, Gela- 

 tin. — In the animal body w T e find that food is required for at 

 least three purposes : First, to build up the organism at the 

 outset, or, in other words, to secure its first growth. Second, 

 to maintain the organism at its normal standard after its 

 growth is complete, or to furnish material to supply the waste 

 which is perpetually going on while life lasts. Third, to 

 maintain the proper temperature of the system. Hence there 

 must be at least two kinds of material contained in the food: 

 one that will sustain and promote the growth of the tissues 

 called histogenetic, and another that will keep up the heat of 

 thj body to a proper standard, called calorifacient. The first 

 of these requisites is found in food containing Nitrogen, called 

 azotised, and the other in that with no Nitrogen, called non- 

 azotised. Of the azotised food the most important constituents 

 are Albumen, Fibrine, Casein, and Gelatin. Albumen is fami- 

 liarly known as the transparent portion of an egg before it is 

 cooked, or the white of the egg after a cooking process. It ex- 

 ists also in the blood, muscles, and bones of all animals*, and is 



How is its alkaline character serviceable ? What other processes does it accomplish ? 

 321. What three purposes is food required for ? Hence what two kinds of food must b© 

 brought into the system ? Give examples of azotised food. 



