TOXINS AND ANTITOXINS 



47 



one hour. The Rosenau glass syringe for this purpose has an 

 oblique side arm for salt solution, so that after the toxin-antitoxin 

 mixture is injected, the side arm is swung around, emptying the 

 saline into the main body of the syringe. The salt solution is then 

 injected, thus washing out the remnants of the toxin-antitoxin mix- 

 ture that may remain in the lower part of the syringe and needle. 



The following experiment will serve to illustrate, granting that the pre- 

 liminary titration showed a strength of antitoxin between 1200 and 1-400. 



Dead 

 Dead 

 Dead 

 Dead 

 Dead 

 Dead 

 Dead 

 Dead 

 Dead 

 Dead 



Result 



5 days 

 5 days 

 4 days 

 4 days 

 3 days 

 3 days 

 3 days 

 3 days 

 2 days 

 2 days 



Thus doses i and 2 were more than sufficient to protect four days, and 

 doses 5-10 were insufficient. Doses 3 and 4 protected for four days, and in 

 order to be safe dose No. 3 of 1-240 would be selected. If the antitoxic unit is 

 1/240 of i.o c.c., each c.c. of serum contains 240 units of antitoxin. In com- 

 mercial work, the practice is to be absolutely on the safe side, and the next 

 larger dose of antitoxin would be employed as the unit, and the serum 

 marketed as containing 220 units per c.c. 



In the therapeutic use of such a serum the unit 

 content of the serum is simply a guide to its use, 

 the dose employed being rather on an empirical 

 basis than otherwise, because of the uncertainty of 

 the amount of toxin present in the body of the 

 patient. It is generally assumed that the larger 

 the extent of the exudate, the greater the amount 

 of toxin produced and the larger the absorbing sur- 

 face, but it can readily be seen from the theoretical 

 standpoint that variations may be produced by dif- 

 ferences in toxin production by the different strains 

 of bacillus diphtheriae which may be encountered 

 in patients. It is unwise to stress this latter possi- 

 bility and preferable to regulate the dosage on the 

 former basis. More will be said later regarding 

 therapeusis. 



The Toxin-antitoxin Union. T he E hrlic h 

 Theory. With the foregoing practical considera- 

 tion of antitoxin titration in mind, the theoretical 

 problems of the nature of the toxin-antitoxin com- 

 bination will be taken up. The simplest conception 

 is that antitoxin neutralizes toxin in the same way 

 that a strong acid neutralizes a strong base. As has been seen, 

 the neutralization is quantitative and follows in a general way 



