MATERIAL FROM THE LIVING SUBJECT 227 



ceases, and spinal fluid should flow at once. The fluid should be col- 

 lected in a sterile test tube. Usually from 20 to 30 c.c. of fluid flow 

 spontaneously; the flow may be much greater, 75 c.c. or even more. 

 Rarely but a few drops, or even none at all may be obtained. Normal 

 spinal .fluid is clear and practically colorless. Only a few cells, chiefly 

 lymphocytes, may be found in the sediment obtained by centrifugaliza- 

 tion. Pathologically the fluid may contain numerous cellular elements. 

 A blood-stained spinal fluid may be due to injury to bloodvessels dur- 

 ing the passage of the needle, or to blood from hemorrhage in the brain 

 or upper levels of the cord. In the former case the blood will clot if 

 the spinal fluid is allowed to stand; in the latter case the blood settles 

 to the bottom, but fails to clot. A turbid spinal fluid is indicative of 

 an inflammatory process in the cerebrospinal axis. If the turbidity 

 is uniform, pus cells are almost invariably present. Occasionally the 

 fluid appears clear, but upon standing, solitary, cobweb-like coagula 

 appear, which enmesh cellular elements and bacteria that may be 

 present. Sometimes an artificial stimulus to coagulation is produced 

 by adding a fibre 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, staphy- 

 lococcus, typhoid, colon, influenza or plague bacilli. The fluid is 

 usually more or less turbid. Tubercular infection, which, next to 

 meningococcus infection, is the most common, 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 tuber- 

 cular 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 c.c. of 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 introduced as near the glands as possible, 

 a definite diagnosis of tuberculosis may frequently be made within 

 two weeks; ordinarily four to six weeks are required for the develop- 

 ment of tuberculosis in the guinea-pig. 



For the diagnosis of acute infections of the cerebrospinal axis, about 

 10 c.c. 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 valuable 



