THE CLASSIFICATION OF BACTERIA. 



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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, 



Fig. I. — 1. Coccus, a. 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 1000. 10. Ordinary spirillum — {a) comma- 

 shaped element; (<5) formation of spiral by comma-shaped elements X 1000, 11. Types 

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

 molysis (after Fischer). 14. Bacilli with terminal protoplasm (Biitschli). 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. 

 i3. Thiothrix tenuis (Winogradski). 19. Leptothrix innominata (Miller) . 20. Cladothrix 

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

 (i5) filament showing true branching; (c) filament containing coccus-like bodies ; (rf) fila- 

 ment with club at end. 



