23 
an exposure of eight to ten hours (with the highest temperature on a 
blackened thermometer at 56° C.) and after fifteen hours when the 
temperatme does not exceed 37° C. In the dry state the tetanus 
poison can be exposed to the direct sunlight for one hundred hours 
mthout loss of virulence. Under the action of an electric current 
of 0.5 ampere, continued for two hours, the substance becomes inert. 
Gastric juice destroys the poison through the actiUty of the hydro- 
‘ chloric acid and not by virtue of the pepsin. Ptyalin, diastase, and 
emulsin have no action on it. The effect of tr}"psin has not been 
satisfactorily determined. Putrefactive germs do not destroy the 
poison. The living, but not the dead, intestines of guinea pigs and 
cats destroy its toxicity. The poison may be eliminated by the 
kidneys and retain its properties in the urine; it is not a ferment. 
Ritchie ® states that tetanus toxine under the influence of hydro- 
chloric acid loses vdth comparative readiness its virulently poisonous 
properties. It does not, however, so readily lose its capacity of 
producing immunity, and when all trace of toxicity has disappeared 
the capacity of producing immunity still remains. The less poison- 
ous substances produced in the modified toxine are probably of the 
nature of toxoids. 
Tetanus toxine is also susceptible to the action of alkalies, such as 
sodium hydrate and sodium carbonate, under which it loses its 
toxicity. 
Noguchi,^ 1907, found that eosin, if present in cultures containing 
tetanus spores, prevents the germination of these spores when its 
concentration (in glucose bouillon) reaches 0.2 per cent. 
The toxine production of tetanus bacilli grovm in eosinized culture 
media diminishes as the concentration of the eosin increases. This 
effect is brought about partly by the restraining action of the dye on 
vegetation and partly by its detoxicating action upon the poison. 
The toxine-producing power and the virulence of tetanus bacilli are 
not permanently modified by contact with eosin for a long period or 
by successive cultivations in eosinized media. 
Burckliard^ found that formalin when added to tetanus toxine in, 
the proportion of 1 to 250 was sufficient to protect a mouse against a 
dose of tetanus toxine winch caused the death of the control in twenty- 
four hours. Burckhard does not seem to have determined the fatal 
dose of his tetanus toxine. 
^ Ritchie, James: Artificial modifications of toxins with special reference to immu- 
nity. Journ. hygiene, vol. 1, 1901, pp. 125-144. 
b Noguchi, Hideyo: The nature of the antitetanic action of eosin. Journ. exper. 
med., vol. 9, no. 3, May 25, 1907, pp. 281-290. 
c Burckhard, G.: Zwei Beitrage zur Kenntniss der Formalinwirkung. Centblt. f. 
Bakt., 1 Abt, vol. 18, 1895, pp. 257-264. 
