CLASSIFICATION OF BACTERIA 35 



Sarcina. — Division in three planes, coenobia in bales, or pockets, 

 no flagella. S. ventriculi, frequent in the stomach of men, but non- 

 pathogenic. S. aiirantiaca, flava, luiea are chromogenic. .S'. rosea 

 with red cell contents occurs in swamps, or colors the soil a rose-red 

 color. 



Planococcus. — Division and coenobic formation as in Micrococcus, 

 flagellate. P. citreus produces a yellow color. 



Planosarcina. — Division and coenobic formation as in Sarcina, 

 flagellate. 



Family 2. Bacteriace.e. — Cells longer or shorter cylindric, 

 straight, or at least never spirally twisted. Division always at right 

 angles to the long axis, and only after a preliminary elongation of the 

 cell. The rods may separate early in some species, in others they 

 remain united for a considerable time as longer or shorter filaments. 

 Endospores are frequent, rare, or wanting. Flagella may or may not 

 be present. 



Bacterium (Ehrenberg char, emend.). — Cells as longer or shorter 

 cylindric rods, often forming filaments of considerable length. With- 

 out flagella. Endospore formation in many species, absent in others. 

 Erwin F. Smith ("Bacteria in Relation to Plant Diseases": 168 to 

 171) believes that bacteriologists should substitute Bacterium for 

 Pseudomonas as the older generic name, and he would establish a new 

 generic name Aplanobacter for the non-motile forms generally referred 

 to Bacterium. This distinction is not adopted in this text-book. 

 Pathogenic: Bacterium (Aplanobacter) Rathayi the cause of Rathay's 

 disease of the orchard grass; B. michiganense the cause of the Grand 

 Rapids (Mich.) tomato disease; B. anthracis the first organism deter- 

 mined to be the cause of disease, causing anthrax or splenic fever; 

 B. mallei specific in glanders in men and horses; 5. pneumonice, the cause 

 of pneumonia; B. tuberculosis responsible for tuberculosis (consumption, 

 phthisis) in man and animals. It can be distinguished by its staining 

 reactions. If stained with carbol fuchsin and then treated with dilute 

 nitric acid (1:5), the stain remains fast, while with other organisms, 

 the stain will be washed out. After this treatment the tissues can be 

 treated with methylene blue for differential staining. B. leprcB, the 

 organism of leprosy; B. influenza, the cause of influenza, or grippe; B. 

 diptheritidis, the causal bacterium of diphtheria; B. pestis, specific in 

 the disease known as the plague, which as the Black Death devastated 



