42 INFECTION AND RESISTANCE 



1. When tetanus toxin is injected into the thigh muscles of a 

 guinea pig the poison is found at first only in the sciatic nerve of 

 the same side and in the blood. (The determination of poison was 

 made by injecting macerations of the respective tissues into mice.) 

 If examination was delayed until the symptoms had become general- 

 ized, the poison was found in the opposite sciatic, but the muscle 

 bundles, fat, etc., from the vicinity of the injection area were poison- 

 free. 42 



2. When a nerve is cut poison absorption ceases as soon as axis 

 cylinder degeneration has set in. 



3. If the nerve is cut before the poison is injected the distal 

 end contains poison, the proximal end does not. This again shows 

 that the nerve absorbs the toxin not from its capillaries but solely 

 through the end organs. 



4. If a nerve which already contains poison is severed, toxin 

 will disappear rapidly from the proximal end, since it no longer 

 obtains a renewed supply from the periphery. 



5. If antitoxin is injected into the nerve, above the point of 

 injection, it will successfully bar the way for the ascending toxin. 



6. Severing of the spinal cord prevents the passage of the 

 poison from below upward. 



These facts ascertained in the case of tetanus find their parallel 

 in the phenomena of the distribution of rabic virus 43 as well as in 

 that of poliomyelitis, in both of which there seems to be a progressive 

 centripetal transportation through the nerves. However, in these 

 conditions we are probably dealing not with a poison but with a 

 living virus and, though analogous, the conditions are not entirely 

 comparable. 



From the practical point of view these facts regarding tetanus 

 may explain the frequent failure of therapeutic success attending 

 the injection of tetanus antitoxin after the symptoms of the disease 

 have set in, since in such cases the poison is already distributed to 

 the nerves and is largely inaccessible to the antitoxin. They also 

 have pointed a way toward a more hopeful therapy, namely, the 

 method of injecting the antiserum directly into the nerves about the 

 point of injury. It is not surprising, however, in view of the stated 

 facts, that even this is unsuccessful when done at too late a time, 

 after a considerable amount of poison has already passed above the 

 point of injection to the spinal centers. 



Such selective action on the part of the bacterial poisons is en- 

 tirely analogous to the similar specific action of alkaloids, narcotics, 



42 In view of our discussion of the importance of fats in the absorption 

 of tetanus toxin, it seems inconsistent that the toxin does not concentrate 

 in fatty as well as in nervous tissues. This Meyer explains by the inactive 

 and poorly vascularized condition of the fat tissues. 



43 Di Vestea and Zagari. Fortschr. d. Med., Vol. 6, 1888. 



