88 SPECIAL BACTERIOLOGY 



with sharply defined borders ; later the colonies assume a yellow colour 

 and liquefy the gelatine quickly. 



In Gelatine Stab Cultures. The development takes place along 

 the whole length of the puncture, with accompanying liquefaction of 

 the medium, the growth resembling a stocking. 



On Agar Stroke Cultures. It forms a moist, shiny, gold-coloured 

 elevated growth ; a similar growth occurring on potatoes. 



Bouillon becomes densely clouded with a yellow sediment. 



Milk is coagulated. 



In milk and bouillon lactic acid is chiefly formed. 



Vitality. Cultures remain alive for one year, and are killed in a 

 short time in the steam sterilizer. On silk threads saturated with 

 staphylococci pus, and dried, the cocci are killed by 2 to 3 per cent, 

 carbolic acid in five minutes. 



Pathogenesis. Cutaneous inoculation is negative, but subcutaneous 

 injection causes a local abscess in mice, guinea-pigs, and rabbits ; and 

 intravenous injection in rabbits sometimes causes pyaemia. 



Staphylococcus pyogenes albus. This coccus is identical with 

 the aureus, excepting the absence of the golden pigment. 



Staphylococcus pyogenes citreus. This coccus produces a citron- 

 yellow pigment, but in other respects resembles the aureus. 



Staphylococcus cereus albus and cereus flavus are seldom 

 found, but are characterised by not liquefying gelatine media ; the one 

 exhibits a waxy white pigment, the other a waxy yellow pigment. 



DIFFERENTIAL TABLE. 



A. The Gelatine is liquefied. 



1. Staphylococcus pyogenes aureus. 



2. citreus. 



3. rosaceus. 



4. albus. 



B. The Gelatine is not liquefied. 



1. Staphylococcus cereus flavus. 



2. griseus. 



The Staphylococcus pyogenes aureus is found in furunculus, 

 carbuncles, acute abscesses, circumscribed phlegmons of the skin, 

 impetigo, sycosis, blepharo-adenitis, conjunctivitis phlyctenulosa, 

 acute infectious osteomyelitis, suppuration of lymph-glands, empyema, 

 articular and bursal suppuration, tonsillar abscesses, mammary 



