156 AGRICULTURE. 



of the various parts of the body, as may be seen in the bones 

 of the arm and the fingers. The bones are composed of 

 mineral material, phosphate of lime being the principal con- 

 stituent. In structure, they are more or less porous or cellular. 



MUSCLES. The bones are ingeniously joined together in 

 many places, but to hold them together and to move them 

 muscles are required. In some places these are large and 

 tough, in others they are smaller and more tender. The lean 

 part of an animal's body is a mass of fine muscle fibres. Feel 

 their movement on the inside of the wrist while closing the 

 fist. Grasp your upper right arm, then move the lower right 

 arm up and down. We observe that the muscles that do the 

 most work are the strongest and largest. These muscles are 

 in all parts of the body, crossing and overlapping. By con- 

 tracting and expanding them the animal moves the bones, and 

 therefore the part of the body containing the bones. Around 

 them and over them we sometimes find layers of fat which act 

 as a sort of packing. 



THE ORGANS. In addition to the ordinary muscles, there 

 are the tongue, the throat, the stomach, the heart, the lungs, 

 the liver, the kidneys, the intestines, etc. These are different 

 in shape and different in their uses, but all are very much like 

 the muscles and tendons in composition they may be called 

 structures of muscles formed together into certain definite 

 shapes, so as to do certain definite work. The skin, the hair, 

 the wool, the hoofs, and the horns, that is, the outer parts of 

 an animal, are also made up of the same kind of material as 

 the flesh and muscle. 



BLOOD. "The blood is the life." It flows through all 

 parts of the body, and it is out of it that all the various parts 

 bone, muscle, organs, lean flesh, fat are formed. When we 

 examine blood under a microscope we find that it somewhat 

 resembles milk, as shown in figure 77, page 144. First of all, 

 there is the liquid part, which is called p/asma. In this plasma 



