May 3, 1901.] 
duced into the body. This quantity in the 
case of each serpent varies with its size 
and bodily and mental condition ; with the 
nature of the bite—whether both fangs or 
only one has been introduced, whether they 
have penetrated deeply or only scratched 
the surface ; and with other circumstances 
related to the serpent, such as whether it 
had recently bitten an animal or not, and 
thus parted with a portion or retained the 
whole of the venom stored in the poison 
glands. The quantity required to produce 
death being very exactly related to each 
pound or kilogram of weight.” Fraser 
found the minimum lethal dose per kilo- 
gram to be: “For the guinea-pig (of 
dried venom), 0.00018 gm.; for the frog, 
0.0002 gm.; for the rabbit, 0.000245 gm.; 
for the white rat, 0.00025 gm.; for the cat, 
somewhat less than 0.005 gm.; and for the 
grass snake (Tropedonotus natrix), the rela- 
tively large dose of 0.03 gm.” 
It is significant that the toxicity of cobra 
venom is not the same for all animals. 
Furthermore, it is exceedingly interesting 
to find that the experiments carried out by 
Fraser, in vitro and in the animal organism, 
leave practically no room for doubt that 
the poisonous action of snake venom and 
the antagonistic action of antivenin are 
both chemical. In the unprotected animal 
snake venom injected beneath the skin or 
into the blood stream gives immediate evi- 
dence of reactions of an endothermic char- 
acter; but when in the same manner it is 
introduced into protected animals evidence 
of exothermic reactions is elicited. When 
introduced into the stomach of an animal 
snake venom not only fails to induce symp- 
toms of poisoning, but exhibits a neutraliz- 
ing action upon inoculated venom, and in 
the uninoculated animal confers immunity 
against snake venom. Moreover, the ratio 
between venom and antivenin is quantita- 
tively brought out in the experiments of 
Fraser. All this can be shown to be in 
SCIENCE. 
693 
couformity with well-known chemical laws. 
Numerous examples which illustrate the 
chemical nature of the action of toxalbu- 
mins might be drawn from various intra- 
and intercellular protoplasmic bodies found 
in the vegetable and animal kingdom, but 
time will not permit their multiplication 
here. <A bountiful supply is to be found in 
recent biochemical and medical literature, 
and interested persons are referred to that 
source. 
The specific phenomena of these poisons 
as exhibited in the human body when toxic 
quantities are taken will be found in nearly 
every text-book of modern medicine, so 
there is no need to repeat them here. 
What has been said of the chemistry of 
fermentation is equally applicable here. Spe- 
cific illustrations and their enlargement 
just now would take us beyond the limits 
of this address; for that reason it is well 
to pass on to the consideration of the next 
phase of the subject. 
IMMUNITY. 
The problem of immunity is so closely 
entwined with that of protective inocula- 
tion that it will be easier to discuss the two 
conjointly. 
In its broadest sense, immunity repre- 
sents that state of the living organism (ani- 
mal or vegetable) which enables it to resist 
the toxic action of substances, whether such 
substances be introduced from an external 
source or are developed within the organ- 
ism. Specific immunity is a state of immun- 
ity against a specific substance. This may 
be natural, as when the organism is normally 
non-susceptible; or it may be artificial (ac- 
quired), as in the case of protection against 
disease developed by a previous attack of 
the disease (as in smallpox), or by some 
other artificial means (vaccination, for in- 
stance). 
Vexed as the problem is, much enlight- 
enment is to be gained from an investiga- 
