IMMUNIZATION AND CURE. 203 



The tuberculin is injected subcutaneously, either into the 

 flank or between the shoulder-blades, with an ordinary hypo- 

 dermic or an antitoxin syringe, both the instrument and 

 the site of injection having first been rendered sterile. The 

 reaction usually results in from six to sixteen hours ; on an 

 average in about twelve hours. It is advisable to give the 

 injection at midnight, so that the reaction will occur at a time 

 when both the patient and the attendant are wide awake and 

 alert to note any change in the patient's condition. The re- 

 action is then due some time between 12 noon and 4 o'clock 

 in the afternoon. 



A feeling of chilliness, headache, lassitude, rise in tempera- 

 ture, and increase in the pulse-rate and respiration, sometimes 

 nausea and vomiting, constitute the reaction. An increase of 

 two degrees in the temperature is a positive indication of the 

 presence of tuberculosis. These symptoms usually continue 

 for about thirty hours, and subside gradually. It is best to 

 begin with a small dose, and if no reaction follows, the injec- 

 tion may be repeated with a larger dose at intervals of three 

 or four days until 5 milligrams, the maximum dose, have 

 been administered. If no reaction occurs then, it may be 

 accepted as positive proof that tuberculosis is not present. 



If a reaction follows the injection, the same result cannot be 

 obtained again within at least thirty days. This has been used 

 as a means of perpetrating fraud in the case of cattle which 

 are known to be tubercular. They are injected with tuber- 

 culin, and if another examination is made by the health 

 authorities within the next thirty days their finding will be 

 negative. 



The objection has been raised that the reaction will occur 

 in individuals in whom the tubercular focus or foci may be 

 encapsulated, and that the injection would under these cir- 

 cumstances be the cause of active manifestations of the disease 

 with possibly fatal results. This objection is based on the 

 fact that the reaction has appeared in persons who exhibited 

 absolutely no symptom of the disease. The autopsy on such 

 individuals would doubtless disclose tubercular bronchial or 

 mediastinal lymph-glands. 



Another objection is that the tuberculin may contain viru- 



