228 BACTERIOLOGICAL EXAMINATION OF MATERIAL 



evidence of the etiological organism, and will indicate the medium to 

 use for its isolation and identification. Blood agar is best suited for 

 the meningococcus, parameningococcus, streptococcus and influenza 

 bacillus. The staphylococcus, typhoid, colon and plague bacilli are 

 less fastidious in their requirements. Less commonly, bacteria other 

 than those described above are found in the cerebrospinal fluid follow- 

 ing infection of the sinuses, otitis media, mastoid infection or septi- 

 cemia. The virus of anterior poliomyelitis is also found in the spinal 

 fluid. The most practical method of diagnosis for the latter is to filter 

 the clear spinal fluid through a Berkefeld filter to eliminate all bac- 

 teria, and to inject 5 to 10 c.c. of the filtrate intraspinously into 

 monkeys. The animal usually will exhibit symptoms within two weeks 

 if the virus is present. 



The Examination of Peritoneal, Pleural and Pericardial Fluids. 

 Fluids or exudations from the peritoneum, pericardium or pleurae 

 should be stained by Gram's method to determine the type of organism, 

 and by Wright's method to distinguish the types of cellular elements 

 and their relation to the microorganisms. If the fluid is clear, or if 

 lymphoid cells predominate, an infection with the tubercle bacillus is 

 immediately suggested. Sediment from such a fluid should be injected 

 into a guinea-pig, using the method outlined for suspected spinal fluid. 

 A turbid fluid usually indicates an infection with the streptococcus, 

 pneumococcus, staphylococcus or pneumobacillus, if the material is 

 from the pleurae or pericardium; an infection with the streptococcus 

 or members of the intestinal group if the source is the peritoneal cavity. 

 Rarely the gonococcus has been found. An examination of the Gram- 

 stained smear will indicate the proper medium to use for the isolation 

 of the organisms in pure culture. 



Pus. A Gram stain of pus will indicate, as a rule, the proper medium 

 to use for the isolation and identification of the organisms. Pus from 

 ''cold" abscesses frequently contains no organisms recognizable either 

 by Gram or acid-fast stains; experience has clearly demonstrated, 

 however, that a small amount of the material injected subcutaneously 

 into guinea-pigs will cause their death, frequently within three weeks. 

 At autopsy, tubercles and tubercle bacilli are found in abundance. 

 Much and others believe that tubercle bacilli found in the pus from 

 cold abscesses do not exist in their normal form, but appear as gran- 

 ules the so-called Much granules which are, however, viable and 

 virulent for guinea-pigs. In this animal the organisms regain their 

 normal morphology and staining reactions. The possibility of Hypho- 



