44 MICROBIOLOGY 



practiced as described in the revised Report of the Committee on 

 Standard Methods of the Laboratory Section of the American Public 

 Health Association, 1905. 



(3) The observation of cultural and bio-chemical features shall 

 cover a period of at least 15 days and frequently longer, and shall 

 be made according to the revised Standard Methods above referred 

 to. All media shall be made according to the same Standard 

 Methods. 



(4) Gelatin stab cultures shall be held for 6 weeks to deter- 

 mine liquefaction. 



(5) Ammonia and indol tests shall be made at end of 10th day, 

 nitrite tests at end of 5th day. 



(6) Titrate with N NaOH, using phenolphthalein as an indi- 



20 



cator: make titrations at same times from blank. The difference 

 gives the amount of acid produced. 



The titration should be done after boiling to drive off any CO 2 

 present in the culture. 



(7) Generic nomenclature shall begin with the year 1872 

 (Cohn's first important paper). 



Species nomenclature shall begin with the year 1880 (Koch's 

 discovery of the poured plate method for the separation of organ- 

 isms). 



(8) Chromogenesis shall be recorded in standard color terms. 



TABLE I. 



A NUMERICAL SYSTEM OF RECORDING THE SALIENT 

 CHARACTERS OF AN ORGANISM (GROUP NUMBER) 



100. Endospores produced 



200. Endospores not produced 



10. Aerobic (Strict) 



20. Facultative anaerobic 



30. Anaerobic (Strict) 



1. Gelatin liquefied 



2. Gelatin not liquefied 



0.1 Acid and -gas from dextrose 



0.2 Acid without gas from dextrose 



0.3 No acid from dextrose 



0.4 No growth with dextrose 



.01 Acid and gas from lactose 



.02 Acid without gas from lactose 



.03 No acid from lactose 



.04 No growth with lactose 



