EXAMINATION OF CEREBRO-SPINAL FLUID 69 



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 vertebrae 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 subdural space. When this occurs fluid passes along 

 the needle, sometimes actually spurting out, and should be 

 received in a sterile test-tube. Several cubic centimetres of 

 fluid can thus usually be obtained, no suction being required ; 

 thereafter it can be examined bacteriologically by the usual 

 methods. The depth of the subdural space from the surface 

 varies from a little over an inch in children to three inches, or 

 even more, in adults the length of the needle must be suited 

 accordingly. In making the puncture it is convenient to have 

 either a sterile syringe attached, or to have the thick end of 

 the needle covered with a pad of sterile wool, which is of course 

 removed at once when the fluid begins to flow. It is advisable 

 to use the platinum needles which are specially made for the 

 purpose, as a sudden movement of the patient may snap an 

 ordinary steel needle. 



The Bacteriological Examination of Urine. In such an 

 examination care must be taken to prevent the contamination 

 of the urine by extraneous organisms. In the male it is usually 

 sufficient to wash thoroughly the glans penis and the meatus 

 with 1-1000 corrosive sublimate the lips of the meatus being 

 everted for more thorough cleansing. The urine is then passed 

 into a series of sterile flasks, the first of which is rejected in 

 case contamination has occurred. In the female, after similar 

 precautions as regards external cleansing, the catheter must be 

 used. The latter must be boiled for half an hour, and anointed 

 with olive oil sterilised by half au hour's exposure in a plugged 

 flask to a -temperature of 120 C. Here, again, it is well to 

 reject the urine first passed. It is often advisable to allow the 

 urine to stand in a cool place for some hours, to then withdraw 

 the lower portion with a sterile pipette, to centrifugalise this, 

 and to use the urine in the lower parts of the centrifuge tubes 

 for microscopic examination or culture. 



Filtration of Cultures. For many purposes it is necessary 



