96 A MANUAL OF BACTERIOLOGY 



1. Shake old broth cultures of B. pyocyaneus with chloroform 

 in a separatory funnel until a goodly quantity of pigment is 

 extracted. Evaporate the chloroform from a watch glass. 



2. Study the characters of the organisms grown on gelatin 

 stab, agar slant, milk, and potato. 



3. Make stains with carbol-fuchsin and Gram's stain. 



Exercise 136. Septicaemia, Inflammation, etc. Caused by 

 Streptococcus pyogenes 



This organism may show its pathological effects upon the 

 body in various ways. It may cause suppurative inflammation, 

 erysipelas, septicremia, puerperal fever, pneumonia, or other dis- 

 eases. It frequently invades organs already attacked by other 

 bacteria and causes great injury. In the last stages of pulmonary 

 tuberculosis it is likely to invade healthy tissues adjacent to those 

 affected with tuberculosis, and thus predispose the patient to 

 hemorrhage. " Blood-poisoning " is usually due to an infection 

 of streptococci or staphylococci, or both. 



The virulence of different strains of organisms appears to vary 

 widely. The toxin may be obtained from cultures killed with 

 chloroform or filtered through unglazed porcelain filters. 



Streptococci are always present on the outside of the body, and 

 appear to be capable of causing trouble if they gain entrance 

 when the bodily resistance is low. This emphasizes the necessity 

 of the prompt and thorough disinfection of all wounds. 



1. Make cultures of Streptococcus pyogenes on lactose bouillon, 

 gelatin stab, agar slant, potato, and litmus milk. 



2. After forty-eight to sixty hours shake up the culture in 

 lactose bouillon and make a stained preparation from the gran- 

 ular sediment formed by the bacteria. Also make a stain from 

 the agar slant. Does it stain with Gram's stain ? 



3. Draw and describe the stained preparations with the oil- 

 immersion objective. What is the form and arrangement of the 

 organisms ? How do staphylococci differ ? 



4. Describe all cultures after three days. On which is there 

 no growth ? 



