THE CLASSIFICATION OF BACTERIA. 13 



may be compared to a bunch of grapes, and the species is often 

 called a staphylococcus. Division may take place in two axes at 

 right angles to one another, in which case cocci adherent to each 

 other in packets of four (called tetrads) or sixteen may be found, 



156 



FIG. i. i. Coccus. 2. Streptococcus. 3. Staphylococcus. 4. Capsulated diplococcus. 

 5. " Biscuit "-shaped coccus. 6. Tetrads. 7. Sarcina form. 8. Types of bacilli (1-8 are 

 diagrammatic). 9. Non-septate spirillum X loco. 10. Ordinary spirillum (a) comma- 

 shaped element; (b) formation of spiral by comma-shaped elements X loco., n. Types 

 of spore formation. 12. Flagellated bacteria. 13. Changes in bacteria produced by plas- 

 molysis (after Fischer). 14. Bacilli with terminal protoplasm (Butschli). 15. (a) Bacillus 

 composed of five protoplasmic meshes; (b) protoplasmic network in micrococcus (Butschli). 

 16. Bacteria containing metachromatic granules (Ernst, Neisser) some contain polar 

 granules. 17. Beggiatoa alba. Both filaments contain sulphur granules one is septate. 

 18. Thiothrix tenuis (Winogradski). 19. Leptothrix innominata (Miller) . 20. Cladothrix 

 dichotoma (Zopf ). 21. Stfeptothrix actinomyces (Bostrom), (a) colony under low power; 

 (b~) filament showing true branching; (c) filament containing coccus-like bodies; (d) fila- 

 ment with club at end. 



