HY PER-SENSIBILITY. 393 
Viperine), he would not be likely to die if bitten by any other 
species of South African venomous snake. Such experiments 
are fraught with danger, for if the individual be in the habit 
of drinking alcohol, or if, through over-eating or indulgence in 
a too free meat. diet, his blood should be in an inflammatory and 
impure condition, then blood poison would as likely as not set 
in at the point of the injection, and if death did not occur, sloughing 
of the flesh, more or less extensive, would supervene. 
VARIETY OF VENOMS. 
The venoms of many of the Indian, Australian, American 
and African snakes differ widely in their poisoning properties, 
and therefore it is clear that the serum treatment of snake bite 
is beset with many difficulties. However, if the authorities in 
each of these countries set themselves in real earnest to immunize 
animals to the venom of the most poisonous of the snakes of the 
country, a first-class serum of high anti-toxic power could be 
prepared and sold to the public. The greatest difficulty seems 
to be the collection of sufficient venom for the purpose. 
HYPER-SENSIBILITY. 
A remarkable and mystifying fact in the immunizing of 
animals against snake bite by the injection of graduated doses 
of venom is, that when an animal becomes highly immune and 
is able to tolerate a very great number of ordinarily fatal doses 
without showing any symptoms of poisoning, this high degree 
of immunity often becomes suddenly reversed, and a condition 
of extreme sensitiveness (hyper-sensibility) to snake venom 
sets in, and the animal will succumb even to a very small quantity 
of venom. 
There seems to be a point beyond which tolerance to any 
poison cannot go, and some sudden physiological change takes 
place, doubtless in the cells of the brain, the nerves, and the 
constituents of the blood, making the body susceptible to the 
toxic action of only a small quantity of the poison to which 
the system was hitherto immune, even when given in very large 
doses. 
It is ever thus in scientific research, when one mystery is 
solved others arise, and so it will be to the end. 
