220 



LIFE O'N THE EARTH 



to discover definitely the effects of bacteria on ani- 

 mals. The investigations of Pasteur, Koch, and Lister, 

 an English physician, led to the development of the 

 science of bacteriology. With the establishment of the 

 germ theory of disease and the understanding of in- 



Courtesy Bausch and Lomb Optical Lompany 



FIG. 348. ANTON VAN LEEUWENHOEK (1632-1723) 



fections came new knowledge of immunity, of toxins 

 and antitoxins, and of the theory and practice of in- 

 oculations and vaccinations. 



It would be difficult to estimate the value to the 

 human race of the work of such men as Pasteur, Koch, 



and Lister. Read other 

 books about the lives and 

 works of these men. The life 

 of Louis Pasteur is espe- 

 cially interesting. It is said 

 that when a Paris news- 

 paper, years ago, asked its 

 readers to vote as to who 

 was the greatest living 

 Frenchman, the choice of 

 the people was not a soldier 

 or a politician, but Pas- 

 teur, a man of science. 

 Exercise. In the light of 



William Thompson your sfudy ^ ^ ^^ ^^ 



FIG. 349. LOUIS PASTEUR a paragraph stating clearly 



the obligation of an individual in protecting others when 

 that individual has a contagious disease. 1 



Exercise. Tell what precautions you would use to 

 protect yourself if an epidemic of contagious disease 

 broke out in your community. 



REFERENCES FOR FURTHER STUDY 

 Texts 



Caldwell and Curtis, Science for Today, Chaps. 23, 24 

 Clement, Collister, and Thurston, Our Surroundings, Chaps. 



22, 23, 35 

 Hunter and Whitman, My Own Science Problems, Unit 11 



(part) ; Science in Our Social Life, Chaps. 12-15 

 Lake, Harley, and Welton, Exploring the World of Science, 



Chaps. 28, 32, 33 

 Pieper and Beauchamp, Everyday Problems in Science, Unit 



7 

 Powers, Neuner, and Bruner, The World around Us, Units 2, 



8; This Changing World, Chap. 21; Man's Control of His 



Environment, Chap. 26 



Skilling, Tours through the World of Science, Tour 17 

 Watkins and Bedell, General Science for Today, Chap. 29 

 Wood and Carpenter, Our Environment: How We Use and 



Control It, Unit 7 



Special references 



Ealand, The Romance of the Microscope 

 Kendall, Civilization and the Microbe 

 Conn, Bacteria, Yeast, and Molds in the Home 

 Conn, The Story of Germ Life 

 De Kruif, Microbe Hunters 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. Understand thoroughly what bacteria are, and the 

 conditions under which they grow and reproduce. 



2. Know in what ways bacteria aid us. 



3. Know in what ways bacteria are our enemies. 



4. Understand thoroughly the relationship of bacteria 

 to human diseases. 



5. Know how to guard the human body against in- 

 vasions by disease-producing bacteria. 



TEST OF MASTERY OF THE TOPIC 



In your notebook complete the statements and comply 

 with the instructions. 



1. Bacteria are one-celled 



2. Plants that are hosts for bacteria which take 



from the air are called . 



3. Milk is turned sour by 



4. Three ways in which bacteria are useful to man 

 are . 



5. Five human diseases which are caused by bacteria 

 are . 



6. Disease bacteria in the human body give off poisons 

 called . 



7. The agent used in the treatment of diphtheria is 



8. The modern process of vaccination for smallpox was 

 discovered by 



9. Milk is pasteurized in order to 



10. Write a paragraph discussing various methods in use 

 at the present time to combat disease bacteria. 



1 See workbook, p. 80. 



