46 TUBERCULIN DIAGNOSIS 



It consists, therefore, of a 50 per cent, glycerin extract of the soluble products 

 of metabolism of the tubercle bacillus. 



A part of the glycerin has, however, been used up for the nutrition of the bacteria 

 and thus it is highly probable that after four to six weeks the bouillon contains less 

 than 5 per cent, glycerin and the evaporated solution less than 50 per cent. The 

 specific substances contained within the tuberculin have not been definitely established. 

 As probable elements, however, may be recorded products of secretion of the living 

 bacteria, of degeneration of the dead bacilli and finally the glycerin soluble substances 

 extracted from the bacterial bodies during the heating. No doubt, all these substances 

 and many others about which we lack information, are directly concerned in the activ- 

 ity of the tuberculin. 



Another of the many unsolved questions which here present themselves may be 

 mentioned: whether any substances exist in the filtrate which are thermolabile, and 

 therefore destroyed or modified by the heating? According to Bail's researches, the 

 aggressin of the tubercle bacillus differs from all other aggressins in that it is not 

 thermolabile and can moreover withstand high grades of temperature. In spite 

 of this, though, attempts to eliminate the heating during the manufacturing of the 

 tuberculin should merit consideration. 



If merely the term "Tuberculin" is used, one always has in mind the 

 above filtrate tuberculin, also known as Old Tuberculin. 



The experiment with the tuberculous guinea-pigs has its analogy in 

 the use of tuberculin in the case of man. Here, however, in order to 

 avoid dangerous symptoms far smaller doses of tuberculin are selected. 



If therefore of two individuals one is tuberculous and the 

 The Tuber- other not, and both are injected with the same amount of old 

 culin Reac- tuberculin o.ooi c.cm., the healthy individual remains per- 

 tioninMan. fectly normal while the tuberculous person shows a typical 



symptom complex which can be described under, 



1. General reaction. 



2. Focal reaction. 



3. Local reaction. 



The General Reaction consists of, fever, headache, malaise, nausea, 

 insomnia, cough irritation, palpitation, etc. The most constant symptom 

 is increased temperature; the other manifestations may only be very mild 

 or even entirely absent. 



The Focal Reaction exhibits evidences of a fresh inflammatory process 

 in the suspicious or old tuberculous foci. In cases of lupus, laryngeal, and 

 iris tuberculosis, this inflammatory reaction can be distinctly seen. In 

 pulmonary tuberculosis the previously vague physical signs may now be- 

 come definite; rales may appear, dulness may be increased, and eventually 

 pains in the chest may arise. 



The Local Reaction is noticed at the point of inoculation. In spite of 

 the sterile needle and thorough disinfection, the skin around the site of 

 the injection becomes red, swollen and painful. That this is not due to 

 dirt infection is proven by its absence in non-tuberculous individuals. 



