Pathogenicity, Natural Infection. 443 



without effect as the toxin is not absorbed by the mucous membrane 

 (Ransom) nor is it decomposed by bile and pancreatic juice (Carriere, 

 Vincent). 



The powder obtained from filtrg,tes by precipitation with ammonium 

 sulphate is also toxic, and is so in correspondingly smaller doses (horses, 

 for instance, are killed by 0.006 gram) . 



Tenacity of the toxin. The toxicity of the filtrates suffers hardly any impair- 

 ment by dilution with blood, blood serum or salt solutions, but is diminished upon 

 addition of mineral acids and alkalis. The toxin is precipitated by small amounts of 

 alcohol, and decomposed by large quantities of alcohol. Direct sunlight destroys its 

 effect in 15 to 18 hours, a temperature of 80°G. in 3 hours, mineral acids and alkalis 

 in a concentration of 1% in one hour (KitasatOj Fermi & Pernossi). In powdered 

 form it is much more resistant; at room temperature in a dark place it remains 

 effective for years, while it is gradually attenuated by diffused sunlight; it can 

 stand constant heating to 120°C. and even 135°C. for 15 to 20 minutes, and is 

 destroyed only by 15 minutes' heating to 159 °C. (Morax & Marie). 



Natural infection. This occurs as a rule through contami- 

 nation of wounds on the skin and mucous membranes with 

 bacilli and spores contained in the contaminating medium. The 

 most common carrier of the contagion is earth, less frequently 

 pus or tissue particles emanating from sick animals or cadavers. 

 The bacilli and spores are abundantly distributed in the super- 

 ficial humus layers, especially in such places as contain much 

 manure, especially horse manure; they may also be found in 

 large numbers in the slime of swampy areas. Nicolaier pro- 

 duced the disease in experiment animals by inoculation with 

 garden earth and since then tetanus bacilli have been demon- 

 strated in many regions in garden and farm earth, in street 

 dust, in manure, in various food substances, especially in hay. 

 The experiments have also shown that the bacilli occur in the 

 excrements of healthy horses (Sanchez & Veillon, Nocard), also 

 in those of cattle, hogs and smaller experiment animals 

 (Sormani Strauss, Molinari), for by the inoculation of such 

 material it is frequently possible to produce the disease arti- 

 ficially. (Joseph found tetanus bacilli in the intestinal con- 

 tents of eight cattle examined for this purpose, and believes 

 that they vegetate constantly in older animals.) 



On account of these results which, by the way, also furnish proof that the 

 tetanus bacilli may be present in body cavities and canals, with external openings, 

 without endangering the health of the animal, Verneuil believed that the contagion 

 of tetanus developed originally in the intestinal tract of horses and that tetanus 

 in man always occurred as the result of coming in contact with horses and with 

 straw or earth that had been contaminated with their excrements. It is more likely, 

 however, that the spores gain entrance into the digestive apparatus of horses through 

 dusty food, remain here a time and pass on unchanged into the open (m feces of 

 man, as well as in all carnivora, tetanus spores are very rarely demonstrated). 



Avenues of infection are offered by the various injuries 

 ^ of the skin or mucous membranes, mostly those, however, which 

 are associated with destruction of tissue or accumulation of 

 pathological secretions and which readily come m contact with 

 the earth on account of their location, or those m which foreign 

 bodies have penetrated deeply into the tissues. Especially 



