Antitoxin 407 



If the white mouse is used for testing, one unit must protect 

 against 300,000 minimum fatal doses of toxin. 



The experiments of Lambert * show that a protective 

 power of i : 800,000,000 can be attained. 



This method of testing was first improved by Knorr f and 

 finally made exact and practical according to the ideas of 

 Ehrlich, by Marx.J 



The arbitrary standard unit is contained in a serum 

 carefully tested by the old method until its strength was 

 accurately determined. It is dried, pulverized, and sealed 

 in a vacuum tube with phosphoric anhydride, as in the case 

 of the diphtheria standard test serum, and periodically a 

 tube is opened and the contents dissolved, exactly as in the 

 case of the diphtheria test serum. One c.c. of this serum was 

 able to neutralize 40,000,000 times the fatal toxin dose per 

 gram of white mouse, and of it i c.c. was said to contain 

 one antitoxic unit. 



The test-toxin is prepared from a bouillon culture of the 

 tetanus bacillus, by precipitating with sodium sulphate and 

 desiccating in vacua. The spores of the bacillus collect in 

 immense numbers in the precipitate, and though they do 

 no harm to the animal, not being able to germinate in the 

 body, they interfere with exact results in weighing the 

 powder, so that it is best to redissolve the precipitate, cen- 

 trifugalize the solution for some time to collect the spores, 

 decant the supernatant fluid, and reprecipitate with the 

 ammonium sulphate. The exact strength of this finally 

 refined dried and desiccated toxin is to be carefully deter- 

 mined each time serums are tested, and its variations noted. 

 Carefully prepared, and protected from external injurious 

 agents, such a serum retains its strength almost without 

 alteration. 



When fresh serums are to be tested, two series are to be 

 conducted, one with the standard serum, the other with 

 the unknown. The L + or test dose of toxin is the least 

 quantity which, after the addition of j^Vo" antitoxic unit, 

 not being saturated with antitoxin, is able to kill a white 

 mouse in four or five days. 



T oV(y A.-E. + x 9 Toxin = L . 



* "New York Med. Jour./' June 5, 1897. 



f " Experimented Untersuchungen iiber die Grenzen der Herlun- 

 gesmoglichkrit des Tetanus durch Tetanusheilserum," Marburg, 1895. 



t " Mitteilungen aus der prtifungstechinschen Praxis," Festschrift 

 zum 60 Geburtstage von Robert Koch, Jena, 1903. 



