NEUTRALISATION OF VENOM BY ANTITOXIN 255 
quantity of non-neutralised venom, and that this quantity of venom 
in a free state was insufficient to cause the death of the animal, or 
even any apparent malaise. When multiplied by twenty, however, 
it becomes capable of producing toxic effects; it is for this reason 
that, when it is desired to inoculate a mouse with twenty times the 
lethal dose of 0:00005 gramme neutralised, it is necessary to mix 
with this twenty times lethal dose a dose of serum a little larger 
than twenty times that which renders 0‘00005 gramme of venom 
innocuous to the mouse, that is to say, 1°2 c.c. 
If, instead of making use of the mouse as test animal, we employ 
the rabbit, it is found that the same serum, in a dose of 0°75 c.c., 
 neutralises 0‘001 gramme of venom sufficiently for the mixture to be 
innocuous when inoculated. It is clear that, in this mixture, the 
whole of the venom was not neutralised by the serum, but the 
small quantity left free is incapable of producing harmful effects. 
By this method of employing mixtures of the same dose of 
venom with variable quantities of antivenomous serum, we are 
therefore enabled to determine with the greatest exactness the 
antitoxic power in vitro of each specimen of serum. But it must 
not be forgotten that the result obtained applies only to the species 
of animal into which the mixtures were injected. 
I have already stated (Chapter VIII.) that a fairly close paral- 
lelism exists between the neurotoxic action of venoms and their 
hemolytic action, and I have established that, in order that the 
sensitive red blood-corpuscles may be dissolved under the influence 
of venom, it is indispensable that the reaction take place in the 
presence of normal serum, since venoms have no effect upon red 
corpuscles freed from serum by several successive washings and 
centrifugings. 
Preston Kyes has explained this phenomenon very well by 
showing that the venom combines with the lecithins in the serum, 
or with those contained in the stroma of the corpuscle, so as to 
constitute a hemolysing lecithide. 
The knowledge of this fact enables us to determine, by means 
