170 A MANUAL OF BACTEEIOLOGY 



IV. Pathogenicity 



1. Pathogenic to animals 



Insects, crustaceans, fishes, reptiles, birds, mice, rats, guinea pigs, rabbits, 

 dogs, cats, sheep, goats, cattle, horses, monkeys, man 



2. Pathogenic to plants 



3. Toxins, soluble, endotoxins. 



4. Non-toxin-forming. 



5. Immunity bactericidal. 



6. Immunity nonbactericidal. 



7. Loss of virulence on culture media, prompt, gradual, not observed in 



months. 



(1) The morphological characters shall be determined and described from growths 

 obtained upon at least one solid medium (nutrient agar) and in at least one liquid 

 medium (nutrient broth) . Growths at 37° C shall be in general not older than twenty- 

 four to forty-eight hours, and growths at 20° C not older than forty-eight to seventy- 

 two hours. To secure uniformity in cultures, in all cases preliminary cultivation 

 shall be practiced as described in the revised Report of the Committee on Standard 

 Methods of the Laboratory Section of the American Public Health Association, 1905. 



(2) The observation of cultural and biochemical features shall cover a period of at 

 least fifteen days and frequently longer, and shall be made according to the revised 

 Standard Methods above referred to. AU media shall be made according to the same 

 Standard Methods. 



(3) Gelatin-stab cultures shall be held for six weeks, to determine liquefaction. 



(4) Ammonia and indol tests shall be made at end of tenth day, nitrite tests at end 

 of fifth day. 



(5) Titrate with N/20 NaOH, using phenolphthalein as an indicator ; make titra- 

 tions at same times from blank. The difference gives the amount of acid produced. 



The titration should be done after boiling, to drive off any CO2 present in the 

 culture. 



(6) 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 organisms). 



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



