1 64 AGRICULTURE. 



insoluble portion of the food, that which could not be digested 

 by the secretions of the mouth, stomach, and intestines, and 

 any soluble matter that was unable to get into the blood be- 

 cause of the animal being fed too rapidly or in too large 

 quantity. Its value as a fertilizer will therefore depend upon 

 what we feed and upon how we feed. It may be 'worth much 

 or very little. 



At this point it will be worth turning back and reviewing 

 what has been said about the four stomachs of the ruminants 

 (cattle and sheep), the small single stomach of the horse and 

 the pig, and the long intestines of the pig. 



CIRCULATION OF THE BLOOD. The next question is as to 

 the movement of the blood through the body the circulation 

 of the bloo^d. We start at the heart, which is the headquarters 

 of the blood system, the pumping-station of the system. The 

 heart is made up of muscles which expand and contract and 

 thus give motion to the blood. When the heart stops beating, 

 when it ceases to work, the animal life stops and death takes 

 place. We can feel the beating of our heart. On the inside 

 of the wrist we can feel the throbbing of our pulse. On the 

 side of the head between the ear and the temple we can feel 

 the same throbbing. Where do you find the pulse of a horse, 

 and the pulse of a cow ? 



You have doubtless seen an ox heart; if not, try to get one 

 and examine it. In shape it is like a large pear or egg. There 

 are two divisions, one up and down and one across, dividing it 

 into four compartments. The two smaller divisions in the 

 upper or larger part are called the right and the left auricle, 

 and the two larger lower parts are called the right and the left 

 ventricle. The different parts of the heart are connected with 

 tubes that go to all parts of the body, and the four compart- 

 ments are connected by valves. By the movement of the 

 muscles of the heart the blood is driven along. How is its 

 course directed or controlled ? Perhaps you have seen a mill- 



