49 
different origin the real relation of their potencies. Tizzoni there- 
fore pleads for a simplification and unification of methods, and com- 
mends his o’s^m for general use. Tizzoni prepares two solutions — one 
of toxine and one of serum — the first in distilled water and the second 
in 0.75 per cent salt solution. The two solutions are mixed, and 
after one-half hour of contact the entire mixture is mjected into the 
posterior part of the thigh of a rabbit weighing about 1 kilogram. 
The value of the serum is always calculated upon the titre of the 
mixture which does not cause symptoms in an animal. 
THE FRENCH METHOD OF STANDARDIZING TETANUS ANTITOXIN. 
The strength of the tetanus antitoxin manufactured by the Pasteur 
Institute is not stated upon the packages sold by the Pasteur Vaccine 
Company. The prophylactic dose is given as 10 c. c. It is stated 
that the antitoxic dose of the serum amounts to 1,000,000,000; that 
is, to protect a mouse against the smallest fatal dose it is sufficient 
to use i,ooo; 7 ¥o:ooo of its weight of serum. 
The description of the method used in France was kuidly sent to 
us in a personal communication by Professor Arlomg, of the Bac- 
teriological Institute of Lyons, having been prepared for him by Pro- 
fessor Courmont, who has charge of the control of antitetanic serum 
in that institute. 
A number of guinea pigs are injected under the skin with quanti- 
ties of serum equal to T'otWo.^'o^j 
even ^ . o o o ,o o o of their weight. Twelve to twenty hours afterwards 
they, as well as the controls, are inoculated subcutaneously with a 
single fatal dose of tetanus toxine. The time of death of those which 
develop tetanus is noted. The serum is then said to have an 
immunizing or antitoxic power of so^Loo-j T:oohoo-Q, otc., according 
as the guinea pig which received 5 o ofooo, 1 : 0 oVo 0 o, etc., of its weight 
of serum has survived the injection of tetanus toxine fatal for the 
control. 
Professor Courmont adds that their serum is usually of a strength 
of T;oof.o 00 and never goes below 50 o:ooo* 
The French antitoxic serums are made at the Institut Pasteur, 
Paris, and ITnstitut Bacteriologique, Lyon. 
TABLES FOR DILUTING THE TOXINE AND ANTITOXIN. 
The following tables are used for dilutmg the tetanus toxines and 
antitoxms in this laboratory. They are published not only because 
they will save time and the possibility of error incident to such cal- 
culations, but because it is of some importance that the same methods 
of dilution be used by different laboratories in order that the results 
34493— Bull. 43—08 i 
