20 
The standard toxine under these conditions has sho^vn marked 
stability. After a sojourn of one year (363 days) in a dark clos'et, at 
room temperature, it lost in virulence. It will be recalled that the 
poison was kept in an open vial, loosely stoppered with absorbent 
cotton, so that it had free access to the oxygen and moisture of the air. 
Table No. 8. — Influence of dijfuse light, etc. 
[MLD =0.000,006 gram.] 
Guinea 
pig No. 
Weight 
in grams. 
Date. 
Time of 
death. 
Amount toxine 
subcutane- 
ously. 
Remarks. 
Days. Hours. 
Gram. 
204 
360 
J uly 26, 1906 
' (a) 
0. 000, 008, 1 
205 
375 
do 
4 17 
. 000, 009 
1 36 days at room temperature in diffuse 
206 
375 
.. -do 
5 17 
6 3 
.000,009,9 
.000,011,1 
1 light. 
207 
375 
do 
a Symptoms. 
From this single experiment it will be seen that the toxine exposed 
to diffuse light at room temperature diminished slightly in toxicity 
after thirty- six days of such exposure. 
It is therefore evident that the dried poison, which we use for the 
purpose of standardizing tetanus antitoxin, has sufficient stability 
for practical purposes. 
The work of other investigators upon the stability of tetanus 
toxine and the influence of chemical agents are briefly abstracted in 
the following: 
The first exact work upon the stability of tetanus toxine was done 
by Kitasato ® in 1891. This pioneer paper contains an extensive 
series of tests upon the poison, showing the influence of physical 
agents and a long list of chemical substances. Kitasato found that 
the filtrate of tetanus cultures is very sensitive to heat; 65° C. and 
above is sufficient to destroy it within a few minutes (5 minutes and 
less). It will sometimes withstand 60°C. for fifteen minutes, but 
is destroyed at 60° C. for twenty minutes. 
^It retained its toxic properties when heated an hour and a quarter 
at 55° C., but lost its power after one and a half hours. 
The filtrate of tetanus culture may be dried and retain its toxicity, 
but this depends upon the manner in which the drying is carried out. 
In the dessicator over sulphuric acid the filtrate does not lose its 
properties. The same may be said if it is dried in the air at room 
temperature, although it is somewhat weakened. 
On the other hand, the filtrate was totally destroyed if it is dried in 
the incubator. The filtrate gradually loses its strength at a tem- 
perature of 35° to 37° C. 
o Kitasato, S.: Experimentelle Untersiichiiiigen liber das Tetanusgift. Zeit. f. 
Hyg., vol. 10, 1891, p. 267-305. 
