43' 
Tests to determine the dose of toxine No. 7. 
Result at autopsy forty-eight hours after inocu- 
lation. 
1 immunity unit -f 0-14 c. c. toxine 
1 immunity unit + .15 c. c. toxine 
1 immunity unit + .16 c. c. toxine 
1 immunity unit -f .17 c. c. toxine 
1 immunity unit + .18 c. c. toxine 
1 immunity unit -f .19 c. c. toxine 
Xo visible reaction. 
No visible reaction. 
Slightest possible congestion about car- 
bon particles, or no reaction. 
Apparent reaction at site of inoculation. 
Injection and edema at site. 
Injection and edema at site. 
The L® dose of this toxine, therefore, is 0.16 c. c. 
These figures are actual results obtained with our toxine No. 7. 
I If the interval between the L+ and the L® dose is greater than 
15xMLD, the toxine contains too great a proportion of toxones, etc., 
and should not be used for testing the strength of antitoxin. If it were 
possible to obtain ideally pure toxines in which the interval between 
I the L-h and the L® dose was only one minimal lethal dose, our prob- 
I lem would be simplified. Unfortunately such a poison has only once 
' i* been demonstrated. However, by these preliminary tests upon a 
‘ ,f number of poisons we select the most suitable for the purposes of this 
; 1? special work. 
^ Having selected a suitable poison, it is now laid aside to season. 
I f For this purpose the toxine should be kept in bulk, so that the process 
S will be uniform throughout the mixture. If it is kept in diffused 
iHight at room temperature, the changes will take place quicker than if 
I kept in the ice box. At intervals of about a month the toxine is tested 
j f in order to determine the rate of change. These examinations will 
!! disclose the fact that the toxicity graduall}" diminishes and the h-f 
' dose increases. These alterations take place progressively until the 
j poison arrives at a stage of equilibrium. Here it may remain for a 
I long time. A short time before this stage of equilibrium is reached it 
' is best to divide the toxine into small bottles, excluding the air, in order 
j to guard against loss by accident or contamination, and store the entire 
I lot in a cold place protected from light. 
I The toxine can not be depended upon for the purpose of testing the 
antitoxin until this stage of equilibrium is reached. After a varying 
j length of time the toxine will again show change in toxicity, and when 
I, this second period of change sets in the toxine should be discarded as 
no longer serviceable for the purposes of these tests. 
As soon as the toxine has reached its stage of stabilit}" or equilil)- 
\ ; rium, that is, when the test dose remains constant, it is necessaiy to 
I i determine this test dose (L+) with the greatest possible accurac}’. 
1 1 The well-standardized toxines used in this laboratory are tested 
