594 



NATURE 



I April 23. 1896 



each case simultaneously administered, are, in the one case, 

 mixed together before injection, and in the other not so mixed, 

 without again having the suggestion originated that the anti- 

 dotism is the result of chemical and not of physiological 

 reactions. 



This suggestion receives a further support from the fact, ob- 

 served in several experiments, that the longer before their 

 administration the two substances were allowed to remain 

 together after they had been mixed, the greater is the antidotal 

 efficiency of the antivenene. Thus, while i '3 cc. per kilo- 

 gramme of antivenene, mixed with five times the minimum-lethal 

 dose of venom, was followed by death when the two had 

 been mixed together five and also ten minutes before adminis- 

 tration, this mixture was, on the other hand, followed by 

 recovery when the interval before the administration was ex- 

 tended to twenty minutes. In order to obtain uniform and 

 comparable results in the first series of experiments, it was 

 therefore found necessary to adhere, in all the experiments made 

 with the larger doses of venom, to a time limitation of not more 

 than ten minutes before the mixed substances were injected. 



I have also administered cobra-antivenene thirty minutes after a 

 dose one-twelfth larger than the minimum-lethal of the venoms, 

 respectively, of the Sepedon hceniachates, the Crotalus horridus, 

 and the Diamentina serpent ; and the animals experimented on 

 have recovered when the dose of cobra-antivenene was not 

 smaller than i '5 cc. per kilogramme. This successful result is 

 all the more remarkable when the intensely destructive effects 

 produced by even smaller doses of each, but especially of two, 

 of these venoms is recollected. 



The antivenene derived from rabbits which had been pro- 

 tected to the extent that they had last received fifteen times the 

 minimum-lethal dose of the Diamentina venom has also been 

 tested against the Diamentina venom itself. When the two 

 were administered together, after having been mixed in vitro, 

 this antivenene in a dose of "05 (1/20) cc. per kilogramme was 

 able successfully to antagonise slightly less than one-and-a-half 

 the minimum-lethal dose of the venom ; but '025 (1/40) cc. per 

 kilogramme failed to do so. 



In the experiments which I have hitherto described, and, 

 indeed, apparently in all others made in this new subject of 

 serum therapeutics, protection has been produced, and the 

 antidotal properties of the antitoxic blood-serum have been 

 tested, by the subcutaneous, or, less frequently, by the intra- 

 venous injection of the venom or other toxic substance. No 

 endeavour seems to have been made to discover how far the 

 same effects, or what effects, may be produced by stomach 

 administration. 



Anticipating that results of an interesting nature might be 

 obtained by this method of administration, I have adopted it 

 for the introduction of both antivenene and venom into the 

 body, and the results have even exceeded my anticipations. 



The plan followed was the simple one of mixing the sub- 

 stances, previously dissolved in water, with a small quantity of 

 milk, and allowing white rats, which had not received any food 

 for several hours previously, to drink this milk. In the mean- 

 time, I will briefly describe only those experiments in which 

 antivenene was thus administered, reserving, for a few minutes, 

 a desfcription of the results that were obtained when the venom 

 itself was used. 



The first experiments were made with the object of determin- 

 ing if, by repeating the process followed in the production of 

 immunity, with the exceptions that the administrations were by 

 the stomach and that antivenene was substituted for venom, an 

 animal could be protected against the poisonous effects of 

 venom. With this object, a white rat received on alternate days 

 during several weeks, doses of antivenene, which were gradually 

 increased from i to 10 cc. per kilogramme, and then, by 

 subcutaneous injection, one-and-a-half the minimum-lethal 

 doses of cobra venom ; with the result that death was not 

 produced. Other white rats received 10 cc. per kilogramme on 

 each of four days, and on the fifth day 15 cc. per kilogramme 

 of antivenene, and still recovery took place when one-and-a-half 

 and one-and-three-quarters the minimum-lethal dose of venom 

 was injected under the skin. To other white rats, 10 cc. and 

 15 cc. of antivenene were given by the stomach, on two 

 successive days, and on the second day, one-and-a-half the 

 minimum-lethal dose of venom, and the result also was that 

 death was prevented. It was thus suggested that a single 

 administration of antivenene might be as efficacious as a 

 succession of administrations ; and accordingly, the antidotal 



efficiency of single doses of 7 and of 10 cc. per kilogramm 

 was tested, in some instances three hours, in others two da) 

 and in others three days before one-and-a-half the minimum- 

 lethal dose of venom was subcutaneously injected ; and in all 

 cases the animals recovered. When, however, 5 cc. per 

 kilogramme of antivenene was thus administered three hours 

 before, and 10 cc. per kilogramme three days before, one-and-;i 

 half the minimum-lethal dose of venom, the animals died. 



The experiments have not as yet been carried further, but I 

 hope to continue them so that the limits of the antidotal power 

 of the antivenene, and the duration of the protection after single 

 doses of antivenene, may be defined. Enough has, however, 

 been done to prove that the stomach administration of anti- 

 venene, equally with its subcutaneous administration, confers 

 protection against lethal doses of serpents' venom, and to justify 

 the use of antivenene by the former and more convenient method 

 for the purpose of securing protection for, at least, a period of 

 several days after a single administration of the protecting 

 antidote. 



The facts hitherto narrated are sufficient to establish that the 

 protection acquired by animals as a result of the administration 

 of venom is not chiefly, or even to any important degree, caused 

 by the venom having produced a tolerance by accustoming the 

 body, as it has been expressed, to the presence of the venom — 

 although a certain degree of this protection may possibly be due 

 to such accustoming — but rather to the presence in the body, as 

 a result of the introduction into it of venom, of a definite 

 substance having antivenomous qualities. Notwithstanding the 

 powerful protective and antidotal action of this substance 

 (antivenene) against serpents' venom, it is instructive to find 

 that it is itself almost devoid of any physiological action, for even 

 very large quantities may be injected under the skin without 

 producing any other physiological reaction than a moderate 

 degree of irritation in the neighbourhood of the injection. How 

 then are we to explain the operation of this physiologically inert 

 substance in protecting an animal against even fifty times the 

 minimum-lethal dose of venom, or by a single administration of 

 it, in saving an animal from death after there has been intro- 

 duced into its body more than twice the quantity of venom that 

 is required to kill it ? When an answer has been attempted to 

 be given to this question in discussions in the wider field of the 

 serum therapeutics which deals with the toxines of diseases, the 

 answer has been found either in the destructive power of 

 phagocytes upon microbes and their toxines, or in the theory 

 that the toxine elaborates from the blood the antidotal anti- 

 toxine, which, whether thus originated or separately introduced 

 into the body, confers upon the body a resisting power which 

 enables it to oppose successfully the injurious action of the 

 toxines. 



These answers cannot solve the problem in so far as snake 

 venom is concerned. Phagocytosis cannot, of course, operate 

 in vitro in solutions which are free from organised structures. 

 Even when solutions of venom and antivenene, mixed together 

 in vitro, have been inserted into the body, it is incredible that 

 the increase in the quantity of antivenene by the i/500th part 

 of a cubic centimetre could cause such an increased prolifera- 

 tion of leucocytes as to prevent a lethal dose of venom from 

 producing death, whereas a dose only the i/5ooth part of a cubic 

 centimetre smaller would be unable to do so. Further, there is 

 no observable increase of leucocytes when much more than these 

 infinitesimal quantities of antivenene have been administered to 

 an animal. 



In view of many of the facts that have to-night been stated, 

 the "resistance of tissues" theory is also untenable. It is 

 opposed, for instance, by the fact that so great a quantity of 

 antivenene as '42 cc, or nearly J of a cubic centimetre per 

 kilogramme is required to prevent death when given thirty 

 minutes before a lethal dose of venom, whereas, for the same dose 

 of venom, only 0004 cc. or the i/25ooth part of a cubic centi- 

 metre, or nearly the i /000th part of the former dose is sufficient, 

 when it is mixed with the venom before administration, and in 

 circumstances, therefore, which are much less favourable for the 

 production by the antivenene of this supposed increase in the 

 resistance of the tissues. 



As I have already pointed out, however, a chemical theory, 

 implying a reaction between antivenene and venom, which 

 results in a neutralisation of the toxic activities of the venom, 

 is entirely compatible with the observed facts. 



The experiments which I have described to-night indicate 

 that, with some limitations in the largest quantities, the greater 



NO. 1382, VOL. 53] 



