282 PA THOGENIC BA CTERIA.

their blood a distinctly potent and valuable antitoxic
substance.

The method for the production of this tetanus anti-
toxic serum is very much like that for the diphtheria
antitoxic serum (q. v.\ except that a much longer time
is required for its production, that the doses of toxin are
of necessity smaller because its toxicity is greater, and
that trichlorid of iodin or Gram's solution will probably
need to be added to the toxin to prevent too powerful a
local reaction. Horses, dogs, and goats may be used.

As tetanus cases are not very common, and the anti-
toxic serum when produced is not very stable in its prop-
erties, Tizzoni and Cattani have successfully prepared it
in a solid form, in which, it is claimed, it can be kept
indefinitely, shipped any distance, and used after simple
solution in water. Their method is to precipitate the
antitoxin from the blood of immunized dogs with alcohol.
Numerous cases of the beneficial action of this antitoxin
are on record.

The strength of the serum is generally expressed
i : 1,000,000, i : 10,000,000, etc., which indicates that i
c.cm. of the serum is capable of protecting 1,000,000 or
10,000,000 grams of guinea-pig from infection.

The experiments of Alexander Lambert show that a
protective power of i : 800,000,000 can be attained.

As Welch has pointed out, the antitoxin of tetanus has
proved to be rather a disappointment in human medicine,
and also for the treatment of large animals, such as the
horse. The results following its injection, in combination
with the sterile toxin, into mice, guinea-pigs, and rabbits
are highly satisfactory, but the amount needed, in pro-
portion to the body-weight, to save the animal from the
toxin being manufactured in its body by bacilli increases
so enormously with the day or hour of the disease as to
make the dosage, which increases millions of times where
that of diphtheria antitoxin increases but tenfold, a matter
of difficulty and uncertainty. Nocard also calls atten-
tion to the fact that the existence of tetanus is unknown