244 PROTEIN POISONS 



anaphylactized animals are interesting and important. 

 He finds that sera from the different horses of the Pasteur 

 Institute, all of the same race, and on the same food, show 

 some, but not marked, variations. On the day that it is 

 drawn, horse serum is highly toxic tested by this method. 

 During the first ten days the toxicity rapidly decreases, 

 after that time more slowly. In making these tests he 

 uses guinea-pigs already used in the standardization of 

 diphtheria antitoxin, and thus saves expense. The standards 

 for therapeutic sera, established by the Frankfurt Institute 

 are as follows: (1) It must be clear and contain no marked 

 deposit. (2) It must not contain bacilli. (3) The highest 

 phenol content must be 0.5 per cent. (4) It must contain 

 no free toxin, especially tetanus toxin. Besredka thinks 

 a fifth requirement should be made, namely, that the D. L. 

 should be less than ^o c - c -> as tested intracerebrally on 

 sensitized guinea-pigs. He makes the following statement 

 concerning the average serum of the Pasteur Institute: 

 The first day it is hypertoxic (D. L. is -^ c.c.); on the 

 eleventh day it has fallen to one-half (D. L. is -$ c.c.); 

 by the forty-fifth day the last-mentioned dose induces 

 severe symptoms, but does not kill; after two months it 

 has fallen to ^ c.c., and after this the decrease is very slow. 

 He thinks it wise not to use a serum less than two months 

 old. In France all therapeutic sera are heated to 50 before 

 distribution, and Besredka states that cases of serum 

 disease are less frequent, and when they do occur, less 

 serious than in countries in which unheated sera are em- 

 ployed. The temperature cannot be raised above 60 

 without weakening the antitoxin. Rosenau and Anderson 

 have tried many chemicals and ferments with the hope of 

 destroying the anaphylactic toxicity of therapeutic sera 

 without injuring the antibody, but with wholly negative 

 results. Other methods of averting the dangers of serum 

 disease will be discussed elsewhere. 



Besredka finds that milk may be heated to 100 for twenty 

 minutes, or to 120 for fifteen minutes without appreciable 

 loss in its anaphylactic toxicity. It begins to lose, however, 



