42 
robic cultures. The inoculated plates and tubes must remain sterile. 
In order to test the quantity of phenol contained in the serimi, a 
mouse weighing 15 grams is mjected subcutaneously with 0.5 c. c. of 
the seriun. If this mouse shows slight or no s^nuptoms of poisoning, 
then the serimi does not contain an excessive amoimt of the preserv- 
ative allowed. 
A guinea pig is then injected subcutaneously with 10 c. c. of the 
serimi in. order to determine the presence of tetanus. If the guinea 
pig remains well, it is considered definite proof that the serum is free 
from this dangerous contamination. For this test it is necessary to 
use healthy, normal animals that have not been previously used for 
other piuposes, so as to avoid the serum reaction.® 
The official testing of antitoxin for potency at Ehrlich^s institute 
is based entdely upon von Behring's method.^ Yon Behring proceeds 
as follows: , 
He dilutes the sermn to be tested vith physiological salt solution 
in the proportion of 1 c. c. of sermn to 99 c. c. of the salt solution. 
One cubic centimeter of this dilution is then placed in an Erlenmeyer 
flask containing 38 c. c. of distilled water, and 1 c. c. of a high-grade 
test poison is added (the test poison Xo. 5 = ^)- imiform mixture 
of these three substances is obtained by shaking and the mixtme is 
then allowed to stand tliirty minutes, when a mouse of mediimi 
weight is injected subcutaneously with 0.4 c. c. If the mouse receiv- 
ing 0.4 c. c. of tliis mixtme remains well, then the serimi contains at 
least 10 immimity units in 1 c. c., because 1 c. c. of the dilution 
1 :100 was entirely neutralized with 1 c. c. of the toxine, representing 0.1 
normal poison. If the mouse after the subcutaneous inoculation of 
0.4 c. c. of the mixture becomes tetanic, then the serum naturally 
contains somewhat less than 10 immunity miits. If the mouse dies, 
we may form some judgment from the time intervening between 
the injection and death as to the approximate value of the serum. 
« Otto, E..; Das Theobald Smithsche Phanomen der Semm-Ueberempfindlichkeit. 
Leuthold-Gedenkschriit, Bd. 1. 
Rosenau, M. J., and Anderson, John F.: A study of the cause of sudden death fol- 
lowing the injection of horse serum. BuU. Xo. 29, Hyg. Lab., L'. S. Pub. Health 
and Mar.-Hosp. Seiw., Wash., 1906. 
Rosenau, M. J., and Anderson, John F.: Studies upon hypersusceptibility and 
immunity. Bull. Xo. 36, Hyg. Lab.. V. S. Pub. Health and Har.-Hosp. Serv., 
Wash.. 1907. 
& Behring and Knorr: L'eber den Immunisierungswert iind Heilwert des Tetanus- 
hellserums bei weissen Mausen. Zeit. f. Hyg., vol. 13, 1893. 
V. Behring: AUg. Therapie der Infektionskrankheiten. Berlin and Vienna, L’rban 
A Schwarzenberg, 1899. • 
^ : Die Wertbestimmung des Tetanusantitoxins tind seine Verwendung in 
der menschenarztlichen und tiemrztlichen Praxis. Deut. med. Woch., 1900, Xo. 2. 
