NEVTBALISATION OF VENOM BY ANTITOXIN 255 



quantity of non-nentralised venoin, and that this quantity of venom 

 in a free state was insufficient to cause the death of the animal, or 

 even any apparent niahiise. When multiphed 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 O'OOOOo 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 000005 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 O'OOl 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. 



13y 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 fJic rcsidt obtained applies oily to tJw species 

 of animal into which the mixtures were injected. 



I have already stated (Chapter YIII.) that a fairly close paral- 

 lelism exists between the murotoxic action cf venoms and their 

 hcBmolytic 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 led 

 corpuscles freed from serum by several successive washings and 

 centrifugings. 



Preston Kyes has explained this phenomenon very well by 

 showing tliat the venom combines with the lecithins in the serum, 

 or with those contained in the stroma of the corpuscle, so as to 

 constitute a lia-molysing lecithide. 



The knowledge of this fact enables us to determine, by means 



