538 THE TETANUS BACILLUS 







earliest symptoms do not appear until between the second and eighth day 

 and death does not occur until 3-10 days after the onset of the symptoms. 



Symptoms and lesions. Whatever the dose inoculated there is, before 

 symptoms appear, a period of incubation the length of which varies with 

 the virulence of the culture, the dose inoculated and the resistance of the 

 animal. As a general rule, the severity of the disease varies inversely as 

 the incubation period the shorter the incubation period the more severe 

 and more rapidly fatal the disease. If the incubation period exceed 5 days 

 in guinea-pigs and 8 days in rabbits, the disease assumes the chronic type, 

 lasts some 10-30 days and may end in the recovery of the animal. 



As in the previous case the symptoms always begin in the neighbourhood 

 of the inoculation and then, if the dose be sufficient, become generalized. 

 If the dose be very small the symptoms may be limited to the limb or group 

 of muscles affected by the inoculation. 



Post mortem. Beyond the occasional occurrence of a little hypersemia or 

 a slight oedema, both very circumscribed, there is no lesion at the site of 

 inoculation. Neither can any lesions be found in the internal organs. 



Cultures of the tetanus bacillus do not multiply when inoculated into the 

 living tissues, but, on the other Hand, the organism quickly disappears. 



Cultures filtered through a Chamberland bougie produce the same symptoms 

 as unfiltered cultures. This matter will be dealt with later, here it is 

 sufficient to point out that the results obtained by inoculating cultures are 

 due to the toxin they contain. 



3. Inoculation Of Spores alone (Vaillard, and Vincent and Rouget). 



If a broth culture of the tetanus bacillus containing spores be heated at 

 80 C. for 3 hours, the toxin is destroyed and the broth contains only spores 

 which remain unaffected by the heating process. 



Doses of 0*5 or 0'6 c.c. of these heated cultures can be inoculated into 

 guinea-pigs without the animal showing any symptoms of tetanus. Pure 

 spores do not germinate in the living, healthy tissues and cannot therefore 

 manufacture the toxin necessary to produce the symptoms of the disease. 

 Spores inoculated in the pure state are rapidly ingested and digested by the 

 phagocytes. 



If however a negatively chemiotactic substance, such for instance as a 

 little drop of lactic acid, be mixed with the spores before inoculation the 

 leucocytes are unable to approach the spores which now, left to themselves, 

 quickly germinate with the result that symptoms of tetanus appear. 



The same result may be arrived at by mechanically protecting the spores against 

 the attacks of the leucocytes. For instance, if the spores be mixed with a little sterile 

 sand and wrapped in a small piece of previously sterilized filter paper, the paper 

 envelope constitutes a defence which the leucocytes cannot penetrate ; the spores 

 therefore are free to germinate and manufacture toxin with the result that the 

 animal dies of tetanus. 



Again, if an injury be produced at the site of inoculation, such as a burn, or a 

 traumatism of the tissues, etc. phagocytosis is interfered with, the leucocytes 

 cannot attack the spores, and the latter develop with the result that the animal will 

 suffer from tetanus. 



Numerous cases of tetanus have been recorded following the hypodermic injec- 

 tion of quinine. Vincent has shown that, like lactic acid, the salts of quinine favour 

 the germination of tetanus spores. In a " carrier " of latent tetanus spores an 

 injection of quinine will be followed by a multiplication of tetanus bacilli at the 

 site of inoculation of the quinine. 



Equally interesting and important in the aetiology of tetanus is the role of 

 ancillary organisms. When an animal succumbs after the inoculation of 



