His veins were mostly gone, retreated back to the bone to escape the probing needle. For a while he used arteries, which are deeper than veins and harder to hit, and for this procedure he bought special long needles. He rotated from his arms and hands to the veins of his feet. A vein will come back in time. Even so, he had to shoot in the skin about half the time. But he only gave up and "skinned" a shot after an agonizing half-hour of probing and poking and cleaning out the needle, which would clot up with blood.