1896.] on Immunisation against Serpents Venom. 125 



producing protection, the greater is the anti-venomous power of the 

 blood-serum, and therefore the larger is the production of the anti- 

 venene. While not an actual proof, this circumstance is at the same 

 time in harmony with the supposition that the antivenene may 

 actually he a constituent of the venom itself. The difficulties en- 

 countered in the separation by chemical methods of the several con- 

 stituents of venom are so great, that it is not probable that the only 

 proof or disproof of this supposition will soon be obtained by chemical 

 analysis. Some physiological experiments which I have made seem, 

 however, to go a long way in supplying the demonstration, which 

 in the meantime has not been obtained from chemistry. 



With the object of determining, in the first place, if the still dis- 

 puted statement is correct, that serpents' venom is inert, or nearly so, 

 when introduced into the stomach of an animal, cobra venom was 

 administered, in a series of gradually increasing doses, to a cat, until 

 finally it had received a single dose eighty times larger than the 

 minimum-lethal ; and to each of six white rats, single doses corre- 

 sponding to 10, 20, 40, 300, 600, and 1000 times the minimum-lethal, 

 if given by subcutaneous injection. Although no poisonous symptoms 

 were produced in the animals by even the largest of these enormous 

 quantities, it was found that the cat had so far been protected, that it 

 could afterwards receive, by subcutaneous injection, one-and-a-half 

 the minimum-lethal dose of cobra venom, without any other injury 

 than some localised irritation at the seat of injection ; and that the 

 white rat, into whose stomach 1000 times the minimum-lethal dose 

 had been introduced by one administration, survived perfectly, when 

 seven days afterwards slightly more than the minimum-lethal dose of 

 venom was injected under the skin. 



It was also found that the blood-serum of the cat was definitely 

 antivenomous, and the curious further fact was ascertained that her 

 progeny had acquired protection through the milk supplied by the 

 protected mother, thus supplying a scientific foundation for a half- 

 admitted conviction, expressed by Wendell Holmes throughout his 

 ' Romance of Destiny,' in regard to the heroine Elsie Venner. 



These significant facts have been extended in a number of other 

 experiments on white rats. In one group of experiments, each animal 

 received, by stomach administration, 500 times the minimum-lethal, 

 if given subcutaneously ; and, as before, no toxic symptoms were 

 observed. On the day following this administration, three of the 

 animals received subcutaneously one-and-a-half the minimum-lethal 

 dose of the same cobra venom, and they all recovered. In one of the 

 other three animals, however, death was caused by this dose, when it 

 was injected only three hours after the stomach administration ; in a 

 second, when this dose was injected two days after the stomach 

 administration ; and in the third, when nearly twice the minimum- 

 lethal was injected twenty-four hours after the stomach administration. 



In a second group of experiments, a dose of cobra venom equiva- 

 lent to 1000 times the minimum-lethal by subcutaneous injection was 



