49 4 



Dr. L. Eogers. On the Physiological 



[Mar. 31, 



The Affinity of the Nervous System for the Poison. 



We have seen that the poison of the Enhydrina is much more potent 

 than even that of Cobra, and it appears to be somewhere intermediate 

 in virulence between Cobra and tetanus toxins. Further, we know 

 that the repeated injection of gradually increasing doses of the latter 

 two poisons into susceptible animals leads to the formation of an anti- 

 toxin in the system. This marked similarity of the nerve poisons of 

 the Colubrine Snakes and tetanus toxin leads one to inquire whether 

 these snake venoms do not exert their noxious influences in the same 

 way that tetanus toxin does, namely, by being taken up from the cir- 

 culation and fixed in the nerve cells until a sufficient dose has been 

 absorbed to paralyse the nervous matter. We know from the experi- 

 ments of Wassermann that small amounts of tetanus toxin can be 

 thus fixed by fresh nerve matter in a test-tube, and so rendered inert 

 when subsequently injected into a susceptible animal. It seemed to 

 be worth while to repeat these experiments with the poison of the 

 Enhydrina, and although I have not had time to carry out a sufficiently 

 exhaustive series of experiments to settle this point, yet the following 

 data appear to me to have some value as being highly suggestive of the 

 mode of action of these nerve-paralysing snake venoms. 



The experiments were carried out in the following manner. A weak 

 solution of the venom, such as is used when giving minimal lethal 

 doses, was placed in a small sterilised test-tube, and a given quantity 

 of fresh brain matter from a pigeon was added to it, and the whole 

 kept at blood temperature for a given time. Another solution of the 

 same strength was kept at the same temperature for an equal period 

 of time without the addition of any brain matter, for the purpose of 

 injecting control animals, which were always used. Double and 

 quadruple minimal lethal doses were used, and the brain matter was 

 broken up so as to mix it with the poison as intimately as possible, 

 and subsequently injected without filtering, so that most of the brain 

 matter in a fine emulsion was injected with the poison. It was found 

 that pigeons injected with these emulsions always lived longer than 

 the control one, while they sometimes recovered from double, and in 

 one instance from quadruple, minimal lethal doses of the poison 

 after being mixed for from half an hour to eighteen hours with a small 

 quantity (from 3 to 20 centigrammes) of fresh brain matter. The 

 most marked effects were obtained by the use of the hemispheres of 

 the cerebrum, the instances of complete recovery from lethal doses 

 having occurred in these instances. The cerebellum had a less marked 

 effect, only considerable prolongation of life having occurred, while in 

 one experiment with the medulla and pons no very marked effect was 

 observed. The grey matter, then, appears to have most effect in 

 fixing the poison, as is also the case with tetanus toxin. These experi- 



