PATHOGENIC EFFECTS 435 



from other thicker bacilli with oval spores placed at a short 

 distance from their extremities, such forms being common in 

 earth, etc., and also met with in contaminated wounds. It is 

 important to note that the wound through which infection has 

 taken place may be very small, in fact, may consist of a mere 

 abrasion. In some cases, especially in the tropics, it may be 

 merely the bite of an insect. In many parts of the world infec- 

 tion through the umbilicus originates a high mortality from the 

 disease in newly born infants. The absence in many cases of a 

 definite channel of infection has given rise to the term " idio- 

 pathic " tetanus. There is, however, practically no doubt that 

 all such cases are true cases of tetanus, and that in all of them 

 the cause is the b. tetani. The latter has also been found in the 

 bronchial mucous membrane in some cases of the so-called 

 rheumatic tetanus, the cause of which is usually said to be cold ; 

 infection of the intestinal mucosa may also occur. 



The pathological changes found post mortem are not striking. 

 There may be haemorrhages in the muscles which have been the 

 subject of the spasms. These are probably due to mechanical 

 causes. It is in the nervous system that we naturally look for 

 the most important lesions. Here there is ordinarily a general 

 redness of the grey matter, and the most striking feature is the 

 occurrence of irregular patches of slight congestion which are not 

 limited particularly to grey or white matter, or to any tract of 

 the latter. These patches are usually best marked in the grey 

 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. 



