39 2 Tetanus 



smaller dose will cause death than is necessary when the 

 poison is absorbed from the subcutaneous tissues. 



Like most of the bacterial toxins, the tetanus poison is 

 only effective when produced in or injected into the tissues 

 and absorbed into the circulation. It is harmless when 

 given by the digestive tract, Ramon* having adminis- 

 tered by the mouth 300,000 times the fatal hypodermic 

 dose without producing any symptoms. The toxin seemed 

 to pass out with the feces. 



One of the most interesting peculiarities about the toxin 

 is the comparative uniformity of the period intervening 

 between its administration and the appearance of the 

 symptoms erroneously called the incubation period. This 

 varies within a narrow margin, inversely, with the size of 

 the dose. Thus, according to Behring, the effect of varying 

 doses of the toxin upon mice becomes evident according 

 to the size of the dose in from twelve to thirty-six hours, 

 thus: 



13 lethal doses symptoms in 36 hours 



1 10 lethal doses symptoms in 24 hours 



333 lethal doses symptoms in 20 hours 



1300 lethal doses symptoms in 14 hours 



3600 lethal doses symptoms in 12 hours 



The local action of the toxin is very painful and asso- 

 ciated with spasm of the muscular fibers with which it 

 comes in contact. Pitfield,f thinking that it might be 

 useful in the treatment of certain paralytic affections, 

 injected a minute quantity of it into the calf of his leg 

 and experienced the severe spasmodic local effects of the 

 poison for twelve hours. 



It has been the belief of most physiologists that tetanus 

 toxin acts solely upon the motor cells of the spinal cord, and 

 produced the tonic spasms as strychnin does. The affinity 

 of the toxin for the nervous tissues has been made the 

 subject of careful investigations by Marie and Moraxf and 

 Meyer and Ransom. The former found that the absorption 

 of tetanus toxin took place partly through the peripheral 

 nerves because of specific affinity between the toxin and 



* " Deutsche med. Wochenschrift," Feb. 24, 1898. 

 t "Therapeutic Gazette," March 15, 1897. 



J "Ann. de 1'Inst. Pasteur," 1902, xvi, p. 818; and "Bull, de 1'Inst. 

 Past.," 1903, i, p. 41. 



"Arch. f. exper. Path. u. Pharmak.," 1903, xux. 



