112 



VETERINARY BACTERIOLOGY 



broth. The characters to be noted are presence or absence of 

 coagulation, type of curd produced, whether or not whey is extruded, 

 peptonization or digestion of the casein, acid production, con- 

 sistency, and changes in color of the medium. 



Litmus Milk. In addition to the preceding, acid or alkali 

 production and reduction of the litmus are to be noted. 





Fig. 59. Types of growth in stab cultures: A, Non-liquefying: 1, Filiform 

 (B. coli); 2, beaded (Str. pyogenes); 3, echinate (Bact. acidi lactici); 4, villous 

 (Bact. murisepticum) ; 5, arborescent (B. mycoides). B, Liquefying: 6, 

 Crateriform (B. vulgare, twenty-four hours) ; 7, napiform (B. subtilis, forty- 

 eight hours); 8, infund^mliform (B. prodigiosus) ; 9, saccate (Msp. Finkleri); 

 10, stratiform (Ps. fluorescens) (Frost). 



Gelatin Plate Colonies. Two or three tubes of gelatin are 

 melted, cooled to 40, and one inoculated with a small amount of 

 the organism to be studied. The tube is rolled until the bacteria 

 are thoroughly distributed, and with a platinum loop a transfer 

 is made to a second tube, and from this to a third. The con- 

 tents of each tube are then poured into a Petri dish and allowed 



