144 



BACTERIOLOGY. 



times in the middle of the rod, which becomes swollen centrally, 

 and the spindle-shaped ceil is called a dostridium. Often the spore 

 occurs in the end of the cell; again the whole cell may assume the 

 function of a spore, giving rise to the so-called arthrospore. Spores 

 are designed to perpetuate the species and to this end offer great re- 

 sistance to external influences, such as cold, heat, antiseptics, etc. 

 Dr. Curtis says : "Bacillus antliracis retains its vitality for some 

 time in absolute alcohol and withstands boiling in nutrient solutions 

 for an hour, and has germinated after three years 7 confinement in 

 dry air/' 



Classification of bacteria. The present system of classification 

 is considered imperfect. The outline given below, while not com- 

 plete, will give a fair idea of the scheme, of classification considered 

 most satisfactory by good authorities : 

 Classification: 



Kingdom Vegetable. 



Series Cryptogamia. 



Sub-kingdonx Thallophyta. 

 Class Fungi. 



Sub-class Schizomycetes. 



Sub-class. 



Group. 



Family. 



f Coccaceae 



(spherical) 



Schizomycetes, or 

 Bacteria . . 



Monomor- 

 phous . . 



Genus. 



f Micrococcus. 

 Streptococcus. 

 Diplococcus. 

 Tetracoccus. 

 Staphylococcus. 

 Ascococcus. 

 Sarcina. 



Pleomorphous 



f Spirillum. 

 I Vibrio. 



iBaeteriaeea.J %%$* 

 (rod-shaped) { p^teus 



^ Bacterium. 



SpirulineaB <J Spirulina. 



( Leptothrix. 



Leptotrichese. j CrfiSthrix. 



[ Phragmidiothrix. 



Cladotricheae . \ Cladothrix. 



