ILLUSTRATIONS 



PAGE 



Fig. I. The first drawings of bacteria bj Leeuwenhoek 2 



Fig. 2. Drawings of bacteria after Pasteur (1864) 5 



Fig. 3. Illustrating the close relationhsip of bacteria to the 



blue-green algae 13 



Fig. 4. The normal types of bacteria 23 



Fig. 5. Large bacilli 24 



Fig. 6. Diplococci ,.. 25 



Fig. 7. Streptococci 25 



Fig. 8. Sarcina 26 



Fig. 9. Large spirilla 26 



Fig. 10. Small spirilla 27 



Fig. II. Involution forms of bacilli 27 



Fig. 12. Successive steps in the formation of the various group- 

 ings of the cocci , 28 



Fig. 13. Bacteria with flagella at one pole 29 



Fig. 14. Bacteria with flagella at both poles 30 



Fig. 15. Bacteria with flagella surrounding body 31 



Fig. 16. Capsulated bacteria 31 



Fig. 17. Types of spores 32 



Fig. 18. Yeast cells 34 



Fig. 19. Different types of yeast cells 34 



Fig. 20. A mold colony 35 



Fig. 21. Sterilizers used in bacteriology 43 



Fig. 22. Colonies of bacteria on agar-agar culture media 44 



Fig. 23. Etching of marble by plant roots 79 



Fig. 24. Relationship between crop and bacteria in a soil 93 



Fig. 25. Illustrating nitrogen cycle in nature lOl 



