Above all, the subcutaneous tuberculin test should be used rarely, and then only after all other methods of diagnosis were thoroughly applied. II. CUTANEOUS TUBERCULIN TEST 1. SYNONYMS: Von Pirquet Test or Skin Test 2. APPARATUS AND DILUTIONS NECESSARY: Inoculation needle of Von Pirquet Koch's Old Tuberculin (undiluted or dilutions according to method). A centimeter tape measure (divided to 1/10 cm.) to measure reactions Ether Alcohol lamp Medicine dropper 3. APPLICATION OF TEST: Inner surface of the forearm; clean the site with ether; place two drops of tuberculin 4 inches apart; stretch the skin and scrape off the epidermis (at a point midway between the two drops of tuberculin) by rotating the Von Pirquet needle between thumb and index finger, with slight pressure on the skin; repeat same through the two drops of tuberculin; let the tuberculin soak in for a few minutes. No dressing is necessary. The middle scarification is the control test. One tuberculin and one control test may suffice. A separate needle should be used for the control test. After each inoculation, clean the needle of tuberculin and heat the point red hot in the alcohol flame before applying it again. 4. REACTION: Gradual elevation and reddening of skin around the point of tuberculin inoculation, beginning in 3 hours or later; the reaction (papule) well developed, generally, in 24 hours and most distinct in 48 hours after inoculation. Size of papule varies from a diameter of 10 millimeters in the average case to 20 mm. occasionally, and 30, rarely (Bandelier and Roepke). At the end of 48 hours the swelling and redness subside gradually, with the subsequent bluish discoloration of the skin, remaining for various periods of time, and slight peeling of the epidermis. Individual reactions vary in degree of redness, elevation, size, contour of the border, etc. All these points should be observed and recorded. Time of inspection--24 and 48 hours after inoculation. Single inspection--best time in 48 hours. 5. CAUSE OF REACTION: Interaction between inoculated tuberculin and the antibodies (bacteriolysins, according to Wolff-Eisner) present in the skin of a tuberculous individual; interaction results in hyperaemia and exudation (papule). 6. INTERPRETATION OF REACTION: Occurrence of positive reaction signifies presence of a tuberculous focus somewhere in the body. No indication as to activity or location of the focus. A negative reaction in adults (especially if repeated) signifies non-existence of tuberculosis (unless great deterioration of health, far advanced process, or tolerance to tuberculin established by tuberculin treatment).