OBJECTS.] INTRODUCTORY. 85 



larger proportion. Straw, in fact, which consists of 

 the dry stem and leaves of the wheat plant, is almost 

 wholly made up of cellulose. Besides this, however, 

 it contains a certain proportion of mineral bodies, 

 among them, pure flint or silica ; and, if you should 

 ever see a wheat rick burnt, you will find more or less 

 of this silica, in a glassy condition, in the embers. In 

 the living plant, all these bodies are combined with a 

 large proportion of water, or are dissolved, or sus- 

 pended in that fluid. The relative quantity of water is 

 much greater in the stem and leaves than in the seed. 



57. The Common Fowl and the Sub- 

 stances of which it is Composed. 



Everybody has seen a common fowl. It is an 

 active creature which runs about and sometimes flies. 

 It has a body covered with feathers, provided with 

 two wings and two legs, and ending at one end in a 

 neck terminated by a head with a beak, between the 

 two parts of which the mouth is placed. The hen 

 lays eggs, each of which is inclosed in a hard shell. 

 If you break an egg the contents flow out and are seen 

 to consist of the colourless glairy " white " and the 

 yellow "yolk," If the white is collected by itself in 

 water and then heated it becomes turbid, forming a 

 white solid, very similar to the vegetable albumin, 

 which is called animal albumin. 



If the yolk is beaten up with water, no starch nor 

 cellulose is obtained from it, but there will be plenty 

 of fatty and some saccharine matter, besides substances 

 more or less similar to albumin and gluten. 



The feathers of the fowl are chiefly composed 

 of horn ; if they are stripped off and the body is 



