X 
^26 
) 
There is always a period of incubation in the animal organism. 
The duration of this period varies with the species. As a rule, the 
period of incubation is shorter the more susceptible the animal and 
the higher the dose. According to Behring: 
Incubation 
(hours). 
13 lethal closes per gram, mouse 36 
110 lethal doses per gram, mouse 24/ 
333 lethal doses per gram, mouse 20 
1,300 lethal doses per gram, mouse 14 
3,600 lethal doses per gram, mouse 12 
The period of incubation is never shorter than eight hours. 
We have found in the guinea pig that the period of incubation 
varies inversely with the size of the dose ; that is, within certain limits 
the larger the dose the shorter the period of incubation. This period 
may vary from about eighteen hours to about five days. 
We have found that there is a direct relation between the period 
of incubation and the severity of symptoms in guinea pigs. Guinea 
pigs that show symptoms within forty-eight hours after injections of 
tetanus toxine (either M. L. D. or L + ) invariably die., Guinea pigs 
that show symptoms on The third day usually die, a very small 
percentage recovering. The longer the onset of symptoms is delayed, 
the milder the disease and the greater the chances of recovery. 
These statements are based upon a tabulation of 600 serial cases. 
Tetanus toxine is harmless when given by the mouth. It is not 
absorbed from the intact intestinal tract and is destroyed by the 
digestive juices. 
As a result of work upon guinea pigs. Ransom ® concluded that 
tetanus toxine, even in very large doses, is harmless so long as the 
intestinal tract is intact; that the poison is not absorbed either from 
the stomach or from the intestines, and in consequence neither the 
poison nor its antitoxine appears in the blood; and, finally, that the 
poison is not destroyed in the intestinal canal, but flows through the 
entire canal and is thrown off jper anum. 
Carriere, however, and several other investigators were unable to 
detect any toxine in the excreta after the introduction of large doses 
of toxine by the mouth. 
Carriere ^ accordingly made experiments to determine where teta- 
nus toxine became innocuous. He found that the poison was 
attacked even by the saliva diastase, that pepsin was less injurious, 
that trypsin had considerable action upon it, and that bile in large 
quantity completely destroyed it. He could not detect any influence 
of the intestinal mucous membrane and the intestinal bacteria upon 
' ^ - - ■ 
a Ransom, F. : Das Schicksal des Tetanusgiftes nach seiner intestinalen in den 
Meerschweinorganismus. Deii. med. Woch., vol. 24, 1898, pp. 117-118. 
^Carriere: “Toxines et digestion.” Ann. Past., xiii, 435, 1899 (gives a bibliog- 
raphy of the subject), cf. the General Part. 
