40 METHODS OF OBTAINING HUMAN AND ANIMAL BLOOD 



other obstructions. The stilet is now withdrawn. Usually the first 

 fluid to appear is stained with blood and should be collected in a sep- 

 arate tube. From 5 to 10 c.c. of fluid are then collected in a second 

 sterile tube, the needle is quickly withdrawn, and the puncture wound 

 sealed with collodion and cotton or with adhesive plaster. 



It sometimes happens that, on withdrawing the stilet, no fluid 

 issues forth. In this case the patient is instructed to take a deep 



FIG. 18. TECHNIC OF SPINAL PUNCTURE. 



The patient is sitting on the edge of a chair and is bent forward; the crests of the 

 ilia are indicated by black lines, and are on a level with the spinous process of the 

 fourth lumbar vertebra; the "soft spot" is found just above. The needle is shown 

 in Figs. 141 and 142. The first tube receives the first few drops of fluid, which are 

 usually blood tinged. 



breath, and if fluid does not appear now, the stilet may be inserted 

 gently to dislodge any material that may be occluding the needle, or 

 the needle may be withdrawn a trifle if it has been inserted too far, or 

 may be advanced a little if it has not entered the canal. If, however, 

 the tap proves a dry one, or if only a few drops of blood are obtained, 

 it is not advisable to make another puncture, as the second attempt is 

 likely to prove as unsuccessful as the first. 



