1894 - 95 .] Antivencne and Immunization against Venom. 457 
action. When death is produced by Crotalus venom, the sub- 
cutaneous tissues become extensively infiltrated with a large quan- 
tity of blood and of blood-stained serum, the underlying muscles 
are reduced to an almost pulpy blood-stained substance, and post- 
mortem decomposition occurs very soon after death. Similar 
changes in the subcutaneous tissues, but to a rather less degree, 
are caused by the Diamantina venom, and in addition, hsematuria, 
or more probably hsemoglobinuria, was invariably produced by lethal 
and even by large non-lethal doses. I mention these circumstances 
to indicate the perfection of the protection which is produced by 
the administration of successive gradually increasing doses ; for 
they can be so adjusted that a dose of each venom, even six 
times larger than the minimum-lethal, may be administered without 
producing more than an inconsiderable and often scarcely observable 
degree of local destructive effect. 
In the meantime, the process of protection against the latter 
venoms has not advanced further than six times the minimum^ 
lethal dose. This, however, has been sufficient to allow experi- 
ments to be made by which it has been demonstrated that when 
an animal has acquired a resistant power over more than the 
minimum-lethal dose of one venom, that animal is also abl'e—suc- 
cessfully to resist the lethal action of a dose above the minimum- 
lethal of other venoms. To a rabbit protected against cobra venom, 
a dose above the minimum-lethal of Sepedon venom has been 
administered ; to rabbits protected against Crotalus venom, doses 
above the minimum-lethal of Diamantina and of cobra venoms have 
been given; to rabbits protected against the Diamantina venom, 
doses above the minimum-lethal of Crotalus and Sepedon venoms 
have been given, and in each case the animal has recovered, and 
but few symptoms of injury were produced. At the same time, in 
other experiments, evidence was obtained that animals protected 
against a given venom are capable of resisting the toxic effect of 
that venom more effectually than the toxic effects of other venoms. 
My experiments have not yet proceeded sufficiently far to show 
for what length of time the protection conferred by any final lethal 
dose may last. I propose to make some experiments which will 
give definite information in regard to this point, which may possibly 
lead to practical applications. It has incidentally been discovered, 
