8o AIDS TO BACTERIOLOGY 



closed arm meet. No precaution for exclusion of oxygen 

 is necessary, and spores are said to develop in a day or 

 little longer. Embleton says B. tetani will grow in broth 

 along with Staphylococcus aureus and need no precaution 

 to exclude oxygen. 



Tetanus spores, especially if in a dry condition, keep 

 their virulence for an indefinite time. Much uncertainty 

 exists as to the temperature necessary to kill them. It 

 seems probable that sometimes they withstand boiling 

 for five minutes and require heating in an autoclave for 

 their certain destruction. Embleton says they can stand 

 almost a dull red heat. The resistance of the spores to 

 disinfectants is also high. They survive 5 per cent, phenol 

 solution for fifteen hours. 



Channels of Infection and Pathogenesis. The tetanus 

 bacillus and its spores are found very frequently (90 per 

 cent, of samples) in cow and horse dung and less rarely 

 in human fseces (5 per cent, of samples, Andre wes). It 

 is constantly present in manured land. Unless some 

 degree of penetration into the tissues is effected, the 

 disease does not develop. If only a scratch, abrasion, or 

 superficial cut be suffered, infected material obtaining 

 access thereto seems never to become pathogenic. If 

 manured soil, however, be injected into a laboratory 

 animal, or a stableman or gardener gets wounded with a 

 rusty nail or broken glass, the disease may be produced. 

 The disease is more prevalent in some districts than in 

 others, and by following the statistics of French veterinary 

 surgeons, Bazy (Medical Press, 1915, p. 315) has been 

 able to mark out certain ' accursed fields ' for tetanus 

 just as can be done for anthrax. The disease is prevalent 

 among horses and men on battlefields. The incidence 

 varies with the state of the ground fought over. In the 

 present war the disease is non-existent among troops 

 engaged on uncultivated areas round the Dardanelles just 

 the same as there has been no tetanus in naval cases of 

 wounds. On the highly cultivated grounds of Flanders and 

 France, especially in the Aisne region, cases were not infre- 

 quent. Bazy's statistics bear on 10,396 wounded; of this 

 number 129 developed tetanus, of which 90 proved fatal. 



Umbilical tetanus is common among newborn infants 

 in some countries. Puerperal tetanus and tetanus super- 

 vening after operations are now rare. Impure vaccine 



