In all cases precautions should be taken to avoid throwing of the paraffin mixture directly into the circulation. This is accomplished by passing the needle slowly into the tissues which are to be injected and while the needle is passing through the tissues it should have a strong vacuum suction upon it so that should it strike a vein the blood will immediately begin to flow into the needle. To illustrate how easily blood may be sucked from a vein a hypodermic with a glass barrel may be taken armed with a small needle. If the arm of a patient be allowed to hang down the veins will distend and the point of the needle may be slipped through the skin and into the vein. If the vein is punctured by the needle point the instant the piston of the syringe is drawn back a vacuum forms in the syringe and the blood will flow into the syringe. This same method is to be used in the passage of the larger paraffin needle or any paraffin needle only as the needle is passed along its course the suction should be constantly exerted. This constant suction is secured by simply attaching the half glass syringe to the needle and then as soon as the point of the needle is under the skin the piston is withdrawn and a vacuum formed. Then holding the piston of the syringe out, maintaining the vacuum, the needle is pushed slowly in as far as the operator desires to inject. Should blood begin to flow into the needle at any point the onward passage of the needle is stopped and is withdrawn and re-inserted in a somewhat different direction, particularly if during the withdrawal a point is found where the blood flows steadily into the syringe. If at no point blood flows into the syringe it is plain that no vessel of dangerous size has been punctured by the needle. The veins of the cord are found rather closely around the cord and the cord usually lies below and behind the sac so that should the operator aim to carry his needle point along rather high in the canal he will be least likely to encounter these vessels. It is not to be forgotten that the veins of the cord are particularly likely to be somewhat dilated in these cases of hernia and the operator is taking more or less of a hazard in neglecting the suction technic outlined. It is not safe to trust to the fact that the paraffin is injected in a solid state as is asserted by some operators. It is true that paraffin in a liquid state is more likely to flow into an opened vein than the paraffin in the solid state, yet it is possible to throw a very small amount of solid paraffin into a vein if no precaution is taken to prevent it, and while a very small mass thrown directly into a vein would be harmless in nearly all instances it might do considerable damage should it be so unfortunate as to lodge in certain vessels. FACTORS TO BE CONSIDERED IN DEALING WITH INGUINAL HERNIA.