210 



BACTERIA PATHOGENIC TO MAN 



My own experience with this serum have been few and unsatisfac- 

 tory. 



Development of Agglutinins for Diphtheria Bacilli. By the injec- 

 tions of the bodies of diphtheria bacilli into animals agglutinins have 

 been developed in sufficient amount to act in 1 : 5000 dilutions of the 

 serum. The serum produced from diphtheria bacilli does not agglu- 

 tinate pseudodiphtheria bacilli in high dilutions. The serum of patients 

 convalescent from diphtheria has, as a rule, little agglutinating power. 

 This test is not used in diagnosis. 



Persistence of Antitoxin in the Blood. When injections of toxin are 

 stopped in a horse the antitoxin is slowly eliminated, so that there 

 is a loss of about 20 per cent, a week. In from three to five months 

 all appreciable antitoxin has been eliminated. 



Technical Points upon the Testing of Diphtheria Antitoxin and the Rela- 

 tions between the Toxicity and Neutralizing Value of Diphtheria Toxin. 

 During the earlier investigations the filtered or sterilized bouillon, in 

 which the diphtheria bacillus had grown and produced its "toxin," 

 was supposed to require for its neutralization an amount of antitoxin 

 directly proportional to its toxicity as tested in guinea-pigs. Thus, 

 if from one bouillon culture ten fatal doses of "toxin" were required 

 to neutralize a certain quantity of antitoxin, it was believed that ten 

 fatal doses from every culture, without regard to the way in which it 

 had been produced or preserved, would also neutralize the same amount 

 of antitoxin. Upon this belief was founded the Behring-Ehrlich defini- 

 tion of an antitoxin unit. 



The results of tests by different experimenters with the same anti- 

 toxic serum, but with different diphtheria toxins, proved this opinion 

 to be incorrect. Ehrlich 1 deserves the credit for first clearly perceiving 

 and publishing this. He obtained from various sources twelve toxins 

 and compared their neutralizing value upon antitoxin; these tests gave 

 most interesting and important information. The results in four toxins, 

 which are representative of the twelve, are as shown in the following 

 table: 



' Die Wertbemessung des Diphtherieheilserums und deren theoretisehe Grundlagen. Klinisches 

 Jahrbuch, 1897. 



