The tendency is to overinject a case. One must not forget that the tissues will probably thicken to twice the size of the mass injected. The operator must estimate as nearly as possible the size of the tract to be filled and then aim to throw in enough to about half fill it. The diffusion of the paraffin will usually safely hold the hernia when the patient rises from the table. Should the operator throw in mixtures one and two until the parts are fairly distended and the hernia be not held it is better to use only the plain sterile vaseline for a subsequent injection at the site of the internal ring. If a half dram of vaseline at this point does not hold the hernia a small amount of vaseline may then be thrown in the central portion of the canal. At first the vaseline injections should be used whenever in doubt as to the amount needed above a certain point. As the operator becomes acquainted with the needs of cases by experience the vaseline can be largely substituted by the paraffin mixture number one. TECHNIC TO BE USED IN INJECTING INGUINAL HERNIA. Have a syringe loaded with paraffin mixture number one and another loaded with sterile vaseline. See that the paraffin flows smoothly from the syringe without leaks. See also that the vaseline syringe is working smoothly. Have needles intended for injection of paraffin free from this agent. Place patient on back, thighs flexed slightly or straight if the external ring is easily accessible. Follow the spermatic cord and locate definitely the external ring. Attach empty syringe to needle. Pass needle point through skin. As soon as needle point is through skin exhaust syringe. That is draw piston out to form vacuum in syringe and obtain suction. Pass the needle slowly through external ring and along close to the roof of inguinal canal. When needle is in full length, if no vein has been struck and blood aspirated into the syringe, detach syringe and screw the paraffin syringe tightly to needle. Inject a few drops of paraffin by screwing down syringe. As paraffin is flowing move the point of the needle about in the loose cellular tissue and continuing the injection slowly withdraw the needle. Continue moving the point of the needle in all directions as the needle is withdrawn so that the paraffin will be diffused as much as possible. As the point of the needle emerges between the pillars of the external ring discontinue the injection. Test the effectiveness of the injection. Allow patient to stand on feet. If the hernia reappears have the patient lie down again and reinsert the needle as before described and inject sterile vaseline rather than the paraffin mixture. Not more than enough paraffin to half fill the canal should be injected. If such quantity does not hold hernia sterile vaseline should be used discreetly until hernia is held. The surgeon must estimate the approximate size of the inguinal canal by the size of the external ring.