ELEMENTS OF THE BODY 25 



matter of the red blood cells. The iron gives it the power to carry 

 oxygen from the lungs to all parts of the body. Only one or two 

 grains of iron are required each day to supply the loss of the iron in 

 the body, and several times that amount is eaten daily in our food. 



26. Fats and oils. Fats are a series of smooth, slip- 

 pery substances found in all animals, and in most vege- 

 tables. About five per cent of the human body is fat. It 

 is scattered between the cells of all parts of the body, but 

 in places, as in the walls of the abdomen, it forms thick 

 layers. All fats become 

 liquid when heated, but 

 those that are liquid at 

 ordinary temperatures are 

 called oils. In the living 

 body fat is always in a 

 liquid state, stored in 

 thin-walled pockets made 

 of connective tissue. By 

 boiling, the pockets are Fat tissue (x 100). 



Softened and the fat runs Connective tissue cells form pockets in which 



the liquid fat is stored. 



out upon the water. Each 



pocket is from -^-j--^ to -%^- of an inch in diameter. The fat 

 is produced from the albumin of the cells by a breaking- 

 down process. Fat is a simple substance compared with 

 the complex albumin. Probably all the fat which is stored 

 in the body is made out of albumin. 



27. Emulsion of fat. However much fat may be shaken with 

 water it will remain in tiny particles which soon rise to the surface. If 

 a little white of egg is added, the fat will divide into finer particles and 

 will remain in the water much longer. A mixture of fat and water is an 

 emulsion. No emulsion is permanent, but the fat will rise to the surface 

 in time. Milk is the most perfect emulsion, but even in milk the cream, 

 or fat, rises in a few hours. 



