41 
We aimed to imitate as closely a.^ possible the ordinary conditions 
under which we find glycerinated vaccine on the market. So we 
drew out in the flame a large number of capillary tubes of the length 
and caliber ordinarih^ used by manufacturers to contain material sutfi- 
cient for one vaccination. Definite^ measured amounts of the pure 
culture of tetanus were added to large drops of the glycerinated virus, 
and this mixture was drawn up into the small capillar}^ tubes, which 
were hermeticall}?' sealed in the usual manner. In this way we had an 
accurate gauge of the exact amount of tetanus put into each capillary 
tube. 
These tubes were filled with the glycerinated virus and tetanus 
spores on March 12. Each capillary tube contained one drop of glyc- 
erinated virus plus the following amounts of tetanus culture: 
[.000021 =MLD, miniinal lethal dose.] 
First series =0.000055 c. c. (about MLD). 
Second series .00011 c. c. (about 5 MLD). 
Third series .00022 c. c. (about 10 MLD). 
Fourth series .00040 c. c. (about 20 MLD). 
Fifth series .00074 c. c. (about 40 MLD). 
Sixth series .013 c. c. (about 500 MLD). 
The capillary tubes were tested immediately in mice as a control 
and then placed in the cool chamber at 20^-22° C., protected from 
light, and again tested at intervals in mice and in cultures, as indi- 
cated in the following tables: 
Capillary tubes containing 0.000055 c. c. of tetanus culture added to glycerinated virus, 
March 12, and tested at irdercals as shown. 
[P=positive, i. e., sj'mptoms'of tetanus; N=negative, i. e., no .symptoms; f=death.] 
We see from this series that the tetanus spores neither multiplied nor 
produced toxin. In fact, they gradually lost virulence. Each capil- 
lary tube in this series of experiments contained approximately two 
and a half times the minimal lethal dose of the tetanus culture. It 
