15 'b 



FIG. i. i. Coccus. 2. Streptococcus. 3. Staphylococcus. 4. Capsulated diplo- 

 coccus. 5. " Biscuit "-shaped coccus. 6. Tetrads. 7. Sarcina form. 8. Types 

 of bacilli (1-8 are diagrammatic). 9. Non-septate spirillum X 1000. 10. Ordinary 

 spirillum -(a) comma-shaped element; (6) formation of spiral by comma-shaped 

 elements X looo. 11. Types of spore formation. 12. Flagellated bacteria. 13. 

 Changes in bacteria?'produced by plasmolysis (after Fischer). 14. ,Bacilli with 

 terminal protoplasm (Biitschli). 15. (a) Bacillus composed of five protoplasmic 

 meshes ; (b) protoplasmic network in micrococcus (Biitschli). 16. Bacteria con- 

 taining metachromatic granules (Ernst, Neisser). 17. Beggiatoa alba. Both 

 filaments contain sulphur granules one is septate. 18. Thiothrix tenuis (Wino- 

 gradski). 19. Leptothrix innominata (Miller). '20. Cladothrix dichotoma (Zopf). 

 21. Streptothrix actinomyces (Bostrom), (a) colony under low power ; (b) fila- 

 ment showing true branching ; (c) filament containing coccus-like bodies ; (d.) 

 filament with club at end. 



