380 ISHIGAMI. 



achieving their epoch-making discovery of the serum therapy of tetanus 

 and diphtheria by first attenuating the virus by means of chemical 

 reagents and then immunizing animals with it. Ehrlich's tetanus-toxoid, 

 which is obtained by chemically treating the virulent toxin until it is 

 harmless to animals, still retains the power to immunize them and to 

 neutralize the anti-toxin. 



Considering these facts, it is quite a natural step to apply the same 

 principle to. the subject of tuberculosis and to expect a successful solution 

 of the problem. From my own experience of many years, I find that 

 for the purpose of curing tuberculosis, bacterial immunization is neces- 

 sar} r and that, as the absorption of the tubercle bacilli from the sub- 

 cutaneous tissue of man and animals is extremely difficult, they must 

 first be chemically dissolved and thus made absorbable. 



METHODS OF PREPARING TUBERCULO-TOXOIDIN. 



The culture of the tubercle bacilli is well soaked and washed with 

 water to remove the soluble toxin. It is then thoroughly dried and 

 weighed, and, after washing again with water, it is treated with strong 

 sulphuric acid in order to disintegrate the bacterial body and thus extract 

 the inner-toxin and change its toxicity. Then, after adding a large 

 amount of water, stirring and allowing to stand for some time, the fats 

 and aromatic oil rise to the surface, leaving the active substance in the 

 bottom in the form of a precipitate. This joreeipitate is gathered on a 

 filter paper and well washed with distilled water until it becomes neutral. 

 Five-tenths gram of the dried product is dissolved in 100 cubic centi- 

 meters of a solution of weak alkali to form a brown, clear liquid. 



Although the preparation of tuberculo-toxoidin is such a simple matter, 

 the duration of soaking in the sulphuric acid must be carefully regulated 

 according to the virulence of the bacilli; otherwise the toxicity may still 

 remain too great, or the whole may be rendered useless by carbonization. 

 Therefore, more or less skill in manipulation is required in preparing 

 the toxoidin. 



This substance when injected subcutaneously in man or animals is 

 easily absorbed without local irritation, and, as the toxic property is 

 already changed, comparatively large doses can be injected without harm; 

 yet while it is harmless, it is as effective in immunizing man and animals 

 as Ehrlich's so-called tetanus-toxoid. Hence the name "tuberculo- 

 toxoidin." ' - 



The following experiments on animals demonstrate the efficac} r and 

 harmlessness of the preparation : 



(1) Test of toxicity. — No reaction was obtained by the injection of 10.0 cubic 

 centimeters of the tuberculo-toxoidin into the peritoneal cavity of a tuberculous 

 guinea pig, which would have succumbed in twenty-four hours to an injection 

 of 0.1 cubic centimeter of Koch's old tuberculin. 



