RESPIRATION AND EXCRETION 309 



2. What should be the relationship between the income and 

 outgo columns ? Try to prove it. 



Conclusions. 1. Write a paragraph summing up all the nor- 

 mal changes that take place in the composition of the blood. 



2. What different bodily functions are involved in these 

 changes ? 



b. A Special Change 



Observations 1. Study Figure 78. What is one function 



of the white corpus- 

 cles ? 



2. What happens 

 concerning these cor- 

 puscles in case of cuts, 

 bruises, or splinters ? 



Conclusions. 1. 

 Why are the white 

 corpuscles Of ten called Fm 78 ._ Diagram of a capillary network, show- 

 a kind of " Jack of all ing the white corpuscles creeping through the 

 trades " ? walls of the capillaries to eat bacteria, causing 



o r .!_ JT a boil at rn. 



2. Write an addi- 

 tional note on possible changes in the composition of the blood, 

 due to disease or accident. 



Questions 



1. Which of the organs listed in the table above are purely 

 excretory organs ? Which partly so ? 



2. What are excretions ? 



3. What are the functions of the liver ? 



4. What is the cause of boils ? 



5. Give the cause of the changes that take place in the com- 

 position of the blood in the muscles. 



6. How does the life of one of the body cells remind one of 

 the life of a small animal in a pond ? 



