THE CILIA OF BACTERIA 



19 



classification. With the exception of Cladothrix dichotoma, all the 

 polar cilia are found at the very end of the cell. In the organism 

 mentioned, however, the cilia are a very little distance to the side, 



FIG. 30. Spirillum, showing lophotrich ciliation. 



as is seen in Fig. 15. Cilia are to be found in the round, as well 

 as in the rod and spiral organisms. Fig. 31 shows a preparation of 

 Sarcina ureae, Fig. 32 one of Micro- 

 coccus citreus, and Fig. 33 one of 

 Streptococcus pyogenes. We thus 

 see that all the three great divisions 

 of the cocci-bacteria possess ciliated 

 species. It may be stated gener- 

 ally that all the spiral bacteria 

 have polar, and all the cocci (with 

 the exception of the genus Strepto- 

 coccus) peritrich ciliation. The rod 

 forms have representatives of both kinds. The cilia are always of 

 uniform thickness for the same species, but are undoubtedly thicker 



FIG. 31. Sarcina ureae, showing mode of 

 ciliation characteristic of this genus. 



FIG. 32. Micrococcus citreus, showing cilia. 



and stronger in some than in others. They are never branched, and 

 consist of thin colourless filaments of protoplasm. 



Development of Cilia. The development of cilia has been followed 

 in the case of Spirillum giganteum (often erroneously called Spirillum 

 volutans), in which they are polar and strongly developed. The 



