7 o 



ESSENTIALS OF BACTERIOLOGY 



The colony having been placed under the field of the micro- 

 scope, a long platinum needle, the point slightly bent, is passed 

 between the lens and the plate so as to be visible through the 

 microscope, then turned downward until the colony is seen to 



Fig. 38. Types of growth in stab-cultures: A, Non-liquefying: i, Fili- 

 form (Bacillus coli); 2, beaded (Streptococcus pyogenes); 3, echinate (Bac- 

 terium acidi lactici); 4, villous (Bacterium murisepticum); 5 arborescent 

 (Bacillus mycoides). B, Liquefying: 6, Crateriform (Bacillus vulgare, 

 twenty-four hours); 7, napiform (Bacillus subtilis, forty-eight hours); 8, 

 infundibuliform (Bacillus prodigiosus); 9, saccate (Microsporon Finkleri); 

 10, stratiform (Psorospermum fluorescens) (Frost). 



be disturbed, and the needle is dipped into the colony. This 

 procedure must be carefully done, lest a different colony be 

 disturbed than the one looked at, and an unknown or unwanted 

 germ obtained. 



After the needle has entered the particular colony, it is with- 



