130 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



3. Apparatus for boiling the needle in a dilute solution of 

 washing soda.* 



4. Spray for local anaesthesia. If this is used the hard plaque 

 of skin adds considerably to the difficulty of the operation. If, 

 however, the region be frozen twice, and allowed to thaw after 

 each freezing, the skin will be found to have resumed its normal 

 texture and to be very fairly anaesthetic. 



5. Two or three test-tubes sterilized by dry heat and plugged 

 with dry cotton-wool. 



6. If cultures are to be taken, the tubes of medium should be 

 inoculated at the time of the operation if possible. The medium 

 required will depend to a great extent upon the nature of the 

 organism which is expected. If there are no indications upon 

 this point, the most suitable is solidified blood-serum, but in 

 default of this ordinary agar will answer well. If the case is 

 thought to be one of cerebro-spinal fever, the most suitable 

 medium for the cultivation of the specific organism (Weichsel- 

 baum's Diplococcus intracellularis) is alkaline 5 per cent, glycerin- 

 agar, and a couple of tubes of this should be at hand, as well as 

 blood-serum or ordinary agar. 



Process — i. Preliminary. — As in removal of fluids for bacterio- 

 logical examination from other parts of the body, it is better if the 

 skin can be sterilized some hours before the operation, and a pad 

 soaked in an antiseptic fluid kept on the area until the last 

 moment. This is usually impracticable, and the process will be 

 described as if it were performed at a single visit. 



Put the needle to boil in a weak solution of washing-soda, and 

 proceed to the disinfection of the patient's back. When the 

 needle has boiled for five minutes, remove the vessel from the 

 flame and allow it to cool without removing the needle. 



Place the patient on his left side, and find the processes of the 

 second, third, and fourth lumbar vertebras. A line drawn between 

 the upper points of the iliac crests usually cuts the spine at the 

 upper edge of the spinous process of the fourth lumbar vertebra. 

 Scrub the skin in this vicinity with soap and hot water ; wash the 

 region with alcohol and then with ether, and allow it to dry ; paint 

 on several layers of perchloride lotion, allowing each to soak in 

 before the next is applied ; cover the region with a piece of lint 



* If possible the needle should be sterilized by dry heat previous to the 

 operation, and kept in a tube plugged at both ends with cotton-wool, as in the 

 method recommended for the collection of blood for bacteriological examination. 



