METHOD OF PERFORMING LUMBAR PUNCTURE. 73 



under such conditions (vide special chapters), and if colonies 

 appear the procedure should be repeated to exclude the pos- 

 sibility of accidental contamination. 



{b) But when it is possible a much greater quantity of blood 

 should be obtained to make the examination of any real value. 

 A vein at the bend of the elbow affords the readiest opportunity 

 of getting blood. One proceeds as follows : A bandage is 

 applied tightly around the middle third of the upper arm, and 

 • the skin over the selected area is rendered as aseptic as possible 

 by scrubbing with hot water and soap, washing off the soap 

 with sterile water, wiping with alcohol and ether, and rubbing 

 well with bichloride of mercury, i-iooo. Then the operator, 

 having disinfected his hands, enters a swollen vein with the 

 point of, a syringe of 10-15 c.c. capacity and withdraws not 

 less than 10 c.c. of blood. The puncture made by the syringe 

 is closed with sterile absorbent cotton and collodion. The 

 blood must be quickly distributed amongst six tubes of melted 

 agar and plated, or divided between five flasks containing 

 150-200 c.c. of sterile broth, and these incubated for two or 

 three days and then subjected to study. 



In examining the blood of the spleen a portion of the skin 

 over the organ is sterilised in the same way, a few drops are 

 withdrawn from the organ by a sterile hypodermic syringe and 

 cultures made. (For microscopic methods, vide p. 88 et seq.) 



Bacteriological Examination of the Cerebro-spinal Fluid — 

 Lumbar Puncture. — This diagnostic procedure, which is some- 

 times called for in cases of meningitis, can be carried out with 

 a sterilised " antitoxin needle " as follows : The patient should 

 lie on the right side, with knees somewhat drawn up and left 

 shoulder tilted somewhat forward, so that the back is fully 

 exposed. The skin over the lumbar region is then carefully 

 sterilised, as above described, and the hands of the operator 

 should be similarly treated. The spines of the lumbar vertebras 

 having been counted, the left thumb or forefinger is pressed into 

 the space between the 3rd and 4th spines in the middle line ; the 

 needle is then inserted about half an inch to the right of' the 

 middle line at this level and pushed through the tissues, its 

 course being directed, slightly inwards and upwards, till it enters 

 the sub-arachnoid space. When this occurs fluid passes along 

 the needle, sometimes actually spurting out, and should be 



