28 MANUAI, OF NATURE STUDY. 



improper soil or improper air or poisoned water. 

 That plants grown in one soil and atmosphere will 

 develop into stronger plants than if grown in an- 

 other. Let the pupils give instances. Since the 

 plant which grows in the garden or the timber 

 which makes the frame work of the house must 

 have just the right kind of food and drink, so 

 must the bone of the growing boy have pure blood 

 in order to make strong bone in manhood. Alco- 

 hol and tobacco poison the blood and therefore 

 dwarf the growth of bone. 



Breathing. — a. Organs. b. Process of. c. 

 Purposes, d. Position of body in. e. Bad effects of 

 improper position of body, breathing impure air, 

 improper breathing. 



Lessons. 



1. Begin this subject by a breathing exercise 

 by the whole school. Require the children to take 

 a full breath, by standing erect and closing the 

 mouth. What change is made in form of chest 

 and abdomen while taking a full inspiration? 

 During expiration? What muscles are used most 

 in breathing? Could these muscles act freely if 

 tightly bandaged? Why do we breathe? That 

 which receives the air in inspiration is called the 

 lungs. These lungs surround the heart, which is 

 the blood pump. 



