ELEMENTS OF THE BODY 23 



Water is composed of two gases, hydrogen and oxygen, 

 very firmly united. 



20. Albumin. The protoplasm of the living cells of the 

 body is almost entirely composed of a substance like the 

 white of an egg. Because it turns white when heated, it 

 is called albumin (from the Latin albus, white). Pure 

 albumin is hard and brittle as the white of an egg is when 

 it is dry. In the body it is dissolved in from five to twenty 

 times its own weight of water. This solution in water is 

 what is meant by the albumin of the body. In the blood 

 it is liquid, in the flesh it is somewhat jellylike, and in 

 the skin it is strong and tough. It is a very complex 

 body which only plants can form. Animals must get it 

 from vegetables and change it into their own bodies. 

 When once formed it may become part of the bodies 

 of several successive animals, as one makes food of 

 another. 



Albumin forms the principal part of the protoplasm of 

 all living cells. Some is used in performing the work of 

 the body and does not reach the cells. About four and 

 one half ounces "of pure albumin must be eaten each day 

 to supply the needs of the body. 



21. Forms of albumin. There are many forms of albumin, all 

 having essentially the same properties. The white of eggs is almost 

 pure albumin. Lean meat is composed mostly of another form ; cheese, 

 gelatine, and glue are composed mainly of still other forms. 



22. Coagulation. Most forms of albumin may be hard- 

 ened either by heat or acids, and once hardened they can- 

 not be dissolved again to their original state. A boiled 

 egg illustrates this hardening. Changing a liquid to a 

 jellylike or solid form so that it cannot be changed back 

 to its original form is coagulation. Coagulation of its 

 albumin destroys the life of a cell. 



