328 MEDICAL BACTERIOLOGY 



ing the mixture to stand in a conical glass vessel or, more quickly, by 

 the use of a centrifuge. 2 ) Hammond 's method : 



a. Add 5% of crystallized carbolic acid (in the case of sputum 

 add 5 times its bulk of a 5% solution of carbolic acid). 



&. Place 15 cc. in the tubes of a centrifuge and whirl for 15 

 minutes. 



c. Pour off supernatant fluid and treat precipitate with 3 cc. of a 

 6% KOH solution. Mix thoroughly and allow to stand 2 minutes. 



d. Fill to 15 cc. mark with distilled water and whirl 20 minutes. 



e. Make cover-glass preparation of sediment (or purify same by 

 repeated washings and centrif legalizations with distilled water). 



A centrifugal machine should be able to make at least 2,500 

 revolutions per minute. This speed ought to be maintained for 15 

 minutes. Sputum may be preserved by addition of a small quantity 

 of carbolic acid (5%). 



Negative results are of positive diagnostic value only when re- 

 peated examinations are made of different samples taken at different 

 times. 



EEFERENCES. Em. 75. 



Bacterium influenzae. This micro-organism is frequently pres- 

 ent in enormous numbers (100 or more) and sometimes in almost 

 pure cultures in the greenish purulent masses in the sputum/ It 

 stains readily with the ordinary dyes, and when lightly stained 

 presents the bipolar stain. Carbol-fuchsin diluted 10 times with 

 distilled water is one of the best stains. Gram 's stain is negative. 



Sputum from suspected cases should be collected either by means 

 of a probang, or in a bottle, and examined : 



1) Microscopically by staining, with a weak carbol-fuchsin, 

 smears from the purulent masses. If a very small bacillus is in 

 large clumps, which fails to retain stain by Gram's method, the 

 evidence is strong that it is the influenza bacillus; the diagnosis 

 should be confirmed, however, by 



2) Cultures on blood agar. 



Animal inoculations are without effect. 

 REFERENCES. Em. 64. 



Bacterium pneumoniae (pneumococcus). 



The sputum of patients suffering from pneumonia is usually of 



