486 



Journal of Agricultural Research 



Vol. XIII, No. lo 



Table VI. — Destruction of antitoxin by pepsin and hydrochloric acid {experiment 21) 



[Tetanus antitoxin 420 F. Toxin Fi. Digestion period, 4 days on the day of injection. Total of 36 jruinea 

 pigs in 18 groups of 2 on each dose] 



ANTITOXIN DESTROYED (pER CENT) 



Over 87 



Over 87 



COAGULABLE PROTEIN DIGESTED PAST COAGULABLE STAGE (PER CENT) 



a 10 



95 



AMINO NITROGEN LIBERATED BY DIGESTION (PER CENT) 



17 



oSeep. 481. 



6 Only 2 MLD in i dose of E. 



INTERPRETATION OF ANALYTIC DATA AND INOCULATION TESTS 



The term "unit" or "immunity unit" is used in this work in the 

 sense defined by Rosenau and Anderson {13, p. 6) as follows: 



The immunity unit for measuring the strength of tetanus antitoxin shall be ten times 

 the least quantity of anti tetanic serum necessary to save the life of a 350-gram guinea 

 pig for ninety-six hours against the official test dose of a standard toxin furnished by 

 the Hygienic Laboratory of the Public-Health and Marine-Hospital Service. 



At the time this definition was made (1907) the toxin was the 

 standard and the antitoxin a derived or secondary standard. Accord- 

 ing to this definition, it was immaterial whether the guinea pig died or 

 lived after the 96 hours. At the time of this writing (191 7) the Hygienic 



