The particular form of needle which I have been in the habit of using is shown in the figure. Its lumen has a diameter of 2 mm., and the steel tube ends off flush with the wide shoulder to which the rubber tube is attached. This avoids any recess within the needle in which clotting may begin. The point of the needle should not be too long, in order that it may not wound the opposite side of the vein when it has been introduced. For ease of introduction, however, the extremity should be very sharp and should have cutting edges. The point and edges should be touched up on a bevelled hone each time before the needle is used. The needle should be kept ready for immediate use in liquid paraffin. I have found that the most convenient way of keeping it is to put it into a test-tube containing paraffin, which is plugged with cotton-wool and sterilized at 130° C. in the hot air oven or by careful heating over a flame. In this way the needle may be kept ready for an indefinite time without any chance of its rusting. When it is taken out of the test-tube, a sterile rubber tube is slipped on to it and it is then ready for use. As an additional precaution, a small quantity of paraffin may be drawn up into the rubber tube, which is thus lubricated on the inside, but this is not absolutely necessary. The tube must be sterilized with the rest of the apparatus, as rubber is destroyed by liquid paraffin. [Illustration: Fig. 10.--DRAWING BLOOD FOR TRANSFUSION] When the donor’s arm has been congested by gripping it above the elbow, or better by the application of a tourniquet[9] drawn to the requisite degree of tightness, a suitable vein, usually the median basilic, is chosen. The area of puncture is washed with ether and a very small quantity, 2 to 3 minims, of 2 per cent. novocain is introduced over the vein with a hypodermic syringe. If a larger quantity is used, the vein may become obscured, but this small amount may be dispersed by a few moments’ pressure with the finger, and is usually enough to anæsthetize the very small area of skin that is to be operated upon. A tiny cut in the skin is then made with the point of a scalpel, and the needle is pushed through into the vein. If the donor’s vein is a large one, such as is usually found in the type of donor recommended in a previous chapter, this is quite easy to do. To make it equally easy if the vein be smaller, it has been suggested by Watson that the vein may be fixed by pushing an ordinary fine sewing-needle through the skin at right angles to the line of the vein, into the vein, and out again through the skin. This needle is held with the forefinger and thumb of the left hand, while the right hand pushes the transfusion needle into the lumen of the vein just below it. When the needle is in the vein, the blood flows out rapidly through the tube which hangs into the flask containing the citrate, as illustrated. This flask is held by an assistant, who