Vice-President’s Address. 139 
would mitigate or entirely annul the painful experiences of 
tobacco-poisoning is a question which has not been investi- 
gated to my knowledge, but it has sometimes appeared to me 
that the sons of a man who smokes are often saved the early 
troubles which some young smokers experience. 
This power on the part of the body to become accustomed 
to a poison, which, even in small doses, is fatal under 
ordinary circumstances, is well illustrated in the important 
observations which have been published on serpent venom. 
It has been found that an animal can be rendered immune 
even to cobra poison, either by modifying the poison by the 
action of heat, or, preferably, by inoculating the animal 
with very minute doses of the active venom, so that there is 
obtained a progressive habituation. The venom can also be 
modified, and its activity diminished, by mixing it with a 
chloride of soda or lime. 
The serum of animals thus vaccinated against venom by 
any of these methods possesses immunising properties. A 
mixture of cobra venom with a small quantity of serum 
from an immunised rabbit, may be inoculated into a fresh 
rabbit without producing any untoward action. Further, the 
injection into a rabbit of serum from an immunised rabbit 
enables the animal to tolerate without discomfort twice as 
much venom as would otherwise kill it. The serum has not 
only this protective action, but it even has a curative one, 
for it prevents a fatal issue even when injected some con- 
siderable time after the venom has been introduced. A 
further fact has been established, namely, that animals can 
be rendered immune by administering the pure venom to 
them through the stomach. It has also been shown that the 
serum of a serpent is an antidote to its own venom, and 
even to the venom of other species. The antivenin serum 
from an immunised animal, however, only protects another 
from the poison of the snake originally used. 
In many of the instances to which reference has been 
made, it cannot be proved directly that the mixture of toxin 
with antitoxin, and its consequent neutralisation, is not due 
to a direct action of the latter upon the former. In the case 
of snake venom and antivenin serum this point can be 
