PATHOGENIC EFFECTS 427 



matter of the medulla and pons. Microscopically there is little 

 of a definite nature to be found. There is congestion, and there 

 may be minute haemorrhages in the areas noted by the naked 

 eye. The ganglion cells may show appearances which have 

 been regarded as degenerative in nature, and similar changes 

 have been described in the white matter. The only marked 

 feature is thus a vascular disturbance in the central nervous 

 system, with a possible tendency to degeneration in its specialised 

 cells. Both of these conditions are probably due to the action 

 of the toxins of the bacillus. In the case of the cellular degenera- 

 tions the- cells have been observed to return to the normal under 

 the curative influence of the antitoxins (vide infra). In the 

 other organs of the body there are no constant changes. 



We have said that the general distribution of pathogenic 

 bacteria throughout the body is probably a relative phenomenon, 

 and that bacteria usually found locally may occur generally, and 

 vice versa. With regard to the tetanus bacillus, it is, however, 

 probably the case that very rarely, if ever, are the organisms 

 found anywhere except in the local lesion. 



(b) The Artificially-produced Disease. — The disease can be 

 communicated to animals by any of the usual methods of inocula- 

 tion, but does not arise in animals fed with bacilli, whether 

 these contain spores or not. Kitasato found that pure cultures, 

 injected subcutaneously or intravenously,, caused death in mice, 

 rats, guinea-pigs, and rabbits. In mice, symptoms appear in a 

 day, and death occurs in two or three days, after inoculation 

 with a loopful of a bouillon culture. The other animals 

 mentioned require larger doses, and death does not occur so 

 rapidly. Usually in animals injected subcutaneously the spasms 

 begin in the limb nearest the point of inoculation. In the 

 case of intravenous inoculation the spasms begin in the 

 extensor muscles of the trunk, as in the natural disease in man. 

 In intraperitoneal injection spasms in the muscles controlled by 

 the splanchnic system are an outstanding feature. After death 

 there is found slight hyperasmia without pus formation, at the 

 seat of inoculation. The bacilli diminish in number, and may 

 be absent at the time of death. The organs generally show 

 little change. 



Kitasato stated that in his earlier experiments the quantity of 

 culture medium injected along with the bacilli already contained 

 enough of the poisonous bodies formed by the bacilli to cause 

 death. The symptoms came on sooner than by the improved 

 method mentioned below, and were, therefore, due to the toxins 

 already present. In his subsequent work, therefore, he employed 



