TRYPANOSOMIASIS EXPEDITION TO THE CONGO 
69 
One might conjecture that where the cellular elements are increased the 
examination would be positive for parasites, but the following table shows that this is 
not so evident as might be expected. 
Case 32 shows that, although a large number of parasites were found at each 
puncture, there was an apparent decrease of cells in the fluid. In Case 17, no parasites 
were ever found in the cerebro-spinal fluid, and the cells were invariably scanty ; and 
in the ten cases not proved to be sleeping sickness it will be seen that the cell elements 
of the fluid are almost invariably scanty. In the majority of the early Cases, 19, 39, 
40, 42, 43, 47, 51, whether positive or negative, the cells are scanty or very scanty. 
In Case 28 the cells seem to have disappeared from the fluid in much the same 
proportion as the parasites. In Cases 44 and 49 a very large number of parasites 
was accompanied only by a comparatively small increase of cells. 
For those who are not familiar with the operation of lumbar puncture, I will 
describe the method I have found best. 
The patient is placed on his right side, on a table if possible, with his knees 
drawn up to his face. After thoroughly cleansing his back with soap and water and 
again with alcohol or ether, cocaine is injected, with a short strong needle if the 
patient is a black man, both subcutaneously and deep into the muscles over the 
interspace above the last lumbar vertebra. This interspace is on a straight line drawn 
between the two iliac crests, and the needle should be passed half an inch to the left 
of the middle line, not midway between the two interspinous processes, but slightly 
nearer to the upper one. The next lower space between the sacrum and the last 
lumbar vertebra can be selected if for any reason it is desirable, but owing to the 
flattening of the canal in this situation the operation is not quite so easy to perform 
without drawing blood. 
After waiting a few minutes the knees are adjusted so as to be exactly opposite 
each other, and while the assistant secures the position of extreme flexion, the tips 
of the fingers of the left hand are placed firmly upon the left iliac crest, leaving the 
thumb to indicate not only the interspace but the exact spot and direction as well. 
The puncture needle is then passed through the skin, the precise direction again 
gauged, and the needle then passed on slightly upwards and towards the middle line, 
or downwards and to the right, with reference to the table. If the spot and direction 
have been well chosen, no bone is encountered, the passage of the needle point into 
the canal can easily be felt, and the clear fluid at once appears drop by drop. The 
syringe is then adjusted, and sufficient for examination is slowly drawn off. With a 
little practice and a docile patient no operation is easier, and I have performed it on 
the floor in native huts, in the open bush, in my tent, and in a canoe. Having learnt 
the exact spot and direction, the only difficulty is to gauge the depth to which the 
needle should be passed, for if the point is allowed to prick the cord or the membranes 
opposite, blood immediately appears and the results of the operation are valueless for 
statistical purposes. 
