136 LABORATORY COURSE IN SERUM STUDY 



Materials needed for each student for glanders fixation : 



0.5 c.c. positive glanders serum from a horse known to be infected 



and giving a positive glanders complement fixation reaction. 

 0.5 c.c. normal horse serum. 

 5.0 c.c. glanders antigen. 

 5.0 c.c. guinea pig serum (1-10). 

 5.0 c.c. 5 per cent sheep cells. 

 20 units amboceptor. 

 20 half-inch test tubes. 

 10 one-c.c. graduated pipettes. 

 1 test tube rack. 

 Salt solution. 



LESSON XXII 

 THE STANDARDIZATION OF DIPHTHERIA ANTITOXIN 



(THE proper understanding of the work in this lesson requires 

 a review of the constitution of diphtheria toxins and the theoreti- 

 cal principles involved. The student should read again the sec- 

 tion on toxin and antitoxin in Infection and Resistance, in Kol- 

 mer's Infection and Immunity, in Paul Th. Miiller's Vorlesungen 

 iiber Infektion und Immunitat, in the Krause und Levaditi 

 Handbuch, or in some other work in which these principles are 

 discussed at length.) 



When extensive therapeutic use first necessitated the estab- 

 lishment of a standard of dosage for diphtheria antitoxin, it was 

 hoped that a method could be developed depending upon simple 

 in vitro titration analogous to the titration of normal acid against 

 normal alkali solutions, in which the unknown antitoxin could 

 be measured against known amounts of a standard toxin. Since 

 no visible or chemically determinable reaction takes place between 

 the two substances in the test tube, the only method of ascertain- 

 ing whether or not the given quantity of toxin was neutralized 

 by the antitoxin was to inject the two substances, at first separate 

 but later previously mixed, into susceptible animals and learn 

 from the result whether or not free, unneutralized toxin was left. 

 The guinea pig, chosen as the most suitable test animal, therefore, 

 took the place in these reactions of the " indicator " to demonstrate 



