Mr Myers, The Standardisation of Antivenomous Serum. 329 



therapeutic value. So far to my knowledge, apart from a few 

 isolated recorded cases, there are no statistics yet available. 



At Lille the serum is standardised in the following way. 

 Rabbits of about 2000 grams in weight are employed, and the 

 test dose of the mixture of venoms that is used for immunisation 

 is ascertained. It may be mentioned in passing that this mixture 

 is heated to 73° C. for half-an-hour before use. The test dose 

 chosen is that amount of the mixture which kills the animal in 

 from 15 to 20 minutes when injected intravenously. The amount 

 of serum which will just prevent death when injected 5 minutes 

 before the venom is then determined. This amount of serum is 

 said to contain 2000 units of immunity. 



We now know that for snake poisons, toxin and antitoxin 

 interact directly, and so far as our knowledge goes the process 

 is independent of any vital action. Since the above described 

 method was designed to permit of the supposed stimulation of 

 the cells of the animal by the antitoxin before the toxin is 

 introduced, but does not allow of the completion of the reaction 

 between the two bodies before they enter the blood stream, it 

 must be described as unscientific. 



The first step in the direction of a rational method of 

 standardisation was taken by Semple and Lamb 1 . These authors 

 determined the number of minimal fatal doses contained in 

 Calmette's test dose, and thus gave a value for the serum in 

 terms of its neutralising power, not as in the method above 

 described, in terms of its preventive power. They found that 

 Calmette's test dose for the rabbit amounted to three times the 

 minimal lethal dose for that animal. 



As has been mentioned it is important that the method of 

 standardisation be devised such that the general practitioner 

 may be able himself to ascertain, at all events approximately, 

 the strength of the serum he is about to use. This method is 

 unsuited for this purpose for several reasons. The mixture 

 Calmette uses is complicated, and should be replaced by one 

 single venom, which is easily obtainable. 



Although intravenous injection is a simple operation, sub- 

 cutaneous inoculation is simpler, and if equally accurate is for 

 this reason to be preferred. Calmette heats his venoms to 73° C. 

 for half-an-hour before use. This procedure may render the 

 venom more suitable for immunisation, but as we have clinically 

 to deal with intoxication by unheated venom, it seems a priori 

 preferable to use unheated venom for standardisation. The 

 changes that Cobra poison undergoes on heating to this tempera- 

 ture will be mentioned later. 



i Brit. Med. Journal, Ap. 1, 1899. 



