Duration of reaction, 30 hours or longer. Rise, acme and duration of reaction vary. _b_ Symptoms: May begin with rigor or chilliness, followed by feeling of warmth. Following symptoms may be present: Malaise, giddiness, severe headache, pain in limbs, pain in affected organ, palpitation, loss of appetite, nausea, vomiting, thirst, sleeplessness, lassitude, etc.; in short, a general feeling of "illness." With fall of temperature--disappearance of symptoms. 10. REACTION AT POINT OF INJECTION: Area of redness, swelling, tenderness; important as indicative of sensitiveness, pointing to probable general reaction with repetition or increase of dose. 11. FOCAL REACTION: Reaction at site of process, due to congestion around it. Focal reaction is demonstrable by: _a_ Change in physical signs; breath sounds, resonance, appearance of rales, etc. _b_ Localizing symptoms, pointing to location of the tuberculous process. Lungs--increase of cough, sputum, appearance of bacilli, pain in chest, etc. Kidney--pain in the region of kidney, changes in urine findings, etc. Joint--swelling, tenderness, etc. Lupus--redness and exudation. Focal reaction is an important feature of the subcutaneous tuberculin test; it permits localization of the disease in a certain percentage of cases. Physical examination, sputum examination, urinalysis, etc., are very important _during the course of the reaction_. 12. CONTRAINDICATIONS: Subcutaneous tuberculin test should not be employed in: 1. Cases with temperature above 100° F, by mouth (99.1° F, by mouth, according to Koch). 2. Cases in which the clinical history and physical signs make the diagnosis certain (presence of tubercle bacilli in the sputum render, of course, any other test unnecessary). 3. Cases of recent haemoptysis. 4. Grave conditions, as severe heart disease, nephritis, marked arteriosclerosis, etc. 5. Convalescence from acute infectious diseases, typhoid fever, pneumonia, etc. 13. INTERPRETATION OF THE POSITIVE SUBCUTANEOUS TUBERCULIN REACTION: Occurrence of reaction, following the subcutaneous tuberculin test, signifies the _existence of infection_; it does not signify that the individual is _clinically tuberculous_. To quote E. R. Baldwin, of Saranac Lake: "The tuberculin test is of very limited value in determining tuberculous _disease_; it is of extreme value in detecting tuberculous _infection_." The test results in positive reaction in cases with latent as well as active processes.