For the past three years we have drawn bloods for Wassermann tests with a special instrument which we have found convenient and economical.
As shown in the accompanying illustration, it is a small metal cap which fits the centrifuge tube into which the blood is drawn. The sides of the cap are flexible so that it will fit tubes of varying sizes within a moderate range.
A needle without a hub is sterilized by dry heat in a small test tube with the point of the needle down. When ready for use the needle may be removed without touching the point. It is held by the middle, the wire withdrawn and the butt end of the needle is inserted into a hole in the top of the cap and tightened with a set screw. The cap is placed on the sterile centrifuge tube, and the instrument is ready for use.