36 MYCOLOGY 



London in 1665 in which 70,000 persons perished. It is carried by 

 infested rats. 



N on- pathogenic: B. acelicum sets up in alcohoHc sokition the acetic 

 acid fermentation and its films later form mother of vinegar. B. 

 acidi lactici ferments sweet milk transforming it into sour milk where 

 the acidity is due to lactic acid. B. phosphoreiim is a phosphorescent 

 fresh- water organism. 



Bacillus (Cohn char, emend.). — Cells straight, rod-shaped to ovoid, 

 long or short, sometimes united into filaments. Motile by wavy, 

 bent flagella scattered over the whole surface of the cell. Formation 

 of endospores frequent. Motility may be active for a time, and then 

 is lost. Pathogenic: B. muscB causes the Trinidad banana disease; 

 B. tracheiphilus is responsible for the wilt of cucurbitaceous plants; 

 B. amylovorus, the pear-blight organism; B. carotovorus, specific in 

 soft rot of carrot; B. aroidew, an organism which causes soft rot of the 

 calla; B. tetani, the causal microbe in tetanus, or lockjaw, is found in 

 the soil and may enter the skin or superficial muscles of man through a 

 pin prick, or rusty nail point; B. typhi, the typhoid bacillus. Non- 

 pathogenic: Bacillus subtilis, the hay bacillus found in hay infusion, and 

 is the cause of decay. B. coli in the alimentary canal of animals and 

 men and in the water polluted by sewage. B. butyricus produces 

 butyric acid fermentation and the coagulation of casein. B. radicicola 

 (= Rhizobium leguminosarum) lives in the roots of leguminous plants 

 and forms the root tubercles or nodules (Figs. 8, 9, 10). B. amylobacter 

 (= Clostridium butyricum) ferments cellulose, dissolves casein and is 

 useful in the retting of plants for fiber production. B. prodigiosus 

 is found on many food substances imparting to them a dark red color. 

 B. calfactor appears in hay infusions, where it produces a rise of tem- 

 perature. B. putrificus, a widely distributed organism. Many bacilli 

 that occur in the ocean are luminous. 



Pseudomonas. — Cylindric bacteria, sometimes long, sometimes short, 

 occasionally in threads. Locomotion accomplished by polar flagella, 

 the number of which may vary from one to ten, most frequently 

 one flagellum is present, or three to six. Endospores are formed, but 

 are rare. The following are the causes of diseases in cultivated plants: 

 Pseudomonas campestris is responsible for the black rot of cabbage and 

 other cruciferous plants. Ps. hyacinthi causes the yellow disease of 

 hyacinths. Ps. vascularum is associated as the causal bacterium in 



