LUMBAR PUNCTURE 1 79 



try again in the interspace between the second and third pro- 

 cesses. 



If the patient is able to do so without harm, it is much easier 

 to perform the operation with him sitting" in a chair 

 leaning over the back or on the edge of the bed with his head 

 nearly between his knees, so that the spine is bent into a con- 

 vex curve; by this means the spinous processes are rendered 

 more prominent and the spaces between the laminae are made 

 wider (see Fig. 29). The operation is thus made much more 

 easy, and the method is usually preferable in cases of tabes or 



FIG. 29. OPERATION OF LUMBAR PUNCTURE WITH PATIENT IN 

 SITTING POSITION. 



general paralysis, where the fluid is collected for a cytological 

 examination only, and the patient is in good general health. 

 But the method with the patient on his side should also 

 be learnt. 



3. Collection of Fluid and Inoculation of Media. The first 

 few drops of fluid which escape may be stained with blood; in 

 this case they should be rejected. Allow a few drops of the 

 fluid to flow directly on to the surface of the medium without 

 touching the glass. Collect also some of the fluid (i to 2 

 drachms) in the sterilized empty tube. If no fluid flows 



