MATERIAL FROM THE LIVING SUBJECT 259 
upon standing:, solitary, cobweb-like coap;iila appear, which enmesh 
cellular elements and bacteria that may be present. Sometimes an 
artificial stimulus to coagulation is produced by adding a fiber or 
two of sterile cotton. 
The spinal fluid should be centrifugalized and some of the sediment 
stained with Wright's stain to determine the types of leukocytes and 
organisms present. Polymorphonuclear leukocytes indicate an infec- 
tion with meningococcus, parameningococcus, streptococcus, staphylo- 
coccus, typhoid, colon, influenza or plague bacilli. Pneumococcus 
meningitis is relatively common in young children. The fluid is 
usually more or less turbid. Tubercular infection, which, next to 
meningococcus infection, is the most common in adults, is usually 
accompanied by a clear spinal fluid from which the cobweb coagula 
mentioned above may be obtained upon standing. About 75 per 
cent of cases of tubercular meningitis may be diagnosed through the 
recognition of acid-fast bacilli in the stained smears from these coagula. 
It is essential, in doubtful cases, to inject 1 to 2 cc. of sedimented 
spinal fluid subcutaneously into guinea-pigs. If the inguinal glands 
are injured mechanically by squeezing them between thumb and 
index finger before the injection is made, and the material is intro- 
duced as near the glands as possible, a definite diagnosis of tuberculosis 
may not infrequently be made within two weeks; ordinarily four to 
six weeks are required for the development of tuberculosis in the 
guinea-pig. 
For the diagnosis of acute infections of the cerebrospinal axis, about 
10 cc. of spinal fluid should be withdrawn with aseptic precautions 
into a sterile test-tube. If this fluid is visibly turbid, direct smears 
stained by Gram's stain and with Wright's method will furnish valu- 
able 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, parameningococci, streptococcus and influenza 
bacillus. The staphylococcus, typhoid, colon and plague bacilli are 
less fastidious in their requirements and may be cultured upon ordi- 
nary nutrient media. Less commonly, bacteria other than those 
described above are found in the cerebrospinal fluid following infec- 
tion of the sinuses, otitis media, mastoid infection or septicemia. 
The viruses of anterior poliomyelitis and of lethargic encephalitis are 
also found in the spinal fluid. The most practical method of diag- 
nosis for the latter is said to be to filter the clear spinal fluid through a 
Berkefeld filter to eliminate all bacteria, and to inject 5 to 10 cc. of the 
filtrate intraspinously into monkeys. The animal usually will exhibit 
sym])t()ms within two weeks if the virus is present.' 
The Examination of Peritoneal, Pleural and Pericardial Fluids.— 
Fluids or exudations from the peritoneum, pericardium or pleura* 
should be stained by Gram's method to determine the type of organ- 
1 See section on Poliomyelitis for organisms suspected to be etiological other than 
the filtrable virus. 
