42 INFECTION AND RESISTANCE 



the point of injection takes place entirely by the path of the nerves. 

 That this method of poison distribution might be, among others, 

 an important one was suggested as early as 1892 by Bruschettini, 39 

 who found tetanus toxin in the nerves but not in the adjacent muscle 

 and other tissues surrounding the point of subcutaneous injection. 

 Similar results were obtained subsequently by Hans Meyer, whose 

 experiments were confirmed and extended by Marie and Morax. 40 

 Finally Meyer and Ransom 41 furnished complete proof that the 

 poison was absorbed from the blood and tissues by the peripheral 

 nerve endings alone and was transported centripetally only by the 

 paths of the neurons. The experimental facts elicited may be sum- 

 marized as follows: 



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 ex- 

 amination was delayed until the symptoms had become generalized, 

 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 cen- 

 tripetal transportation through the nerves. However, in these condi- 

 tions 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 



39 Bruschettini. Riforma medica, 1892. 



40 Marie and Morax. Ann. de I'lnst. Past., 1902. 



41 Meyer and Ransom. Archiv f exp. Path. u. Pharm., 49, 1903. 



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. 



