20 THE VITAL PROCESSES 



of an organization, page 10.) In this organization there 

 are to be observed : 



1. A definite arrangement of the cells to form the tis- 

 sues. A tissue is a group of like cells. 



2. A definite arrangement of the tissues in the organ. 

 Each organ contains the tissues needed for its work. 



3. In several instances there is a definite arrangement 

 of organs to form systems. 



4. The body as a whole is made up of organs and sys- 

 tems, together with the structures necessary for their sup- 

 port and protection. 



There now remains a further question for considera- 

 tion. What is the one supreme end, or purpose, toward 

 which all the activities of the body organization are 

 directed ? This purpose will naturally have some relation 

 to the maintenance, or preservation, of the cell group 

 which we call the body. 



The Maintenance of Life. The preservation of any cell 

 group in its natural condition, whether it be plant or animal, 

 is accomplished through keeping it alive. If life ceases, 

 the group quickly disintegrates and its elements become 

 scattered, a fact which is verified through everyday ob- 

 servation. Though the nature of life is unknown, it may 

 be looked upon as the organizer and preserver of the 

 protoplasm. But in preserving the protoplasm it also 

 preserves the entire cell group, or body. Life is thus 

 the most essential condition of the body. With life all 

 portions of the body are concerned, and toward its mainte- 

 nance all the activities of the body organisation are directed. 



The Nutrient Fluid in its Relations to the Cells. The 

 maintenance of life within the cells requires, as we have 

 seen, that they be supplied with water, food, and oxygen, 

 and that they be relieved of such wastes as they form. 



