Tuberculosis. hi 



servant stock owners and veterinariaus of the contagion in 

 tubercle. 



Survival in Water and Moist Earth. — Galtier found that the 

 bacillus tuberculosis was preserved indefinitely in springs, ponds 

 and wells at all ordinar\^ temperatures. Hence the danger of 

 common drinking troughs, of streams that have run'past infected 

 herds, or the places where their manure has been put and of soil 

 that have received the manure or carcasses of the deceased. The 

 danger from soils is less from dust blown from the surface and 

 which has been presumably devitalized by prolonged sunlight, than 

 from the earth that is pulled up attached to the roots of the tur- 

 nips, beets and carrots or to tubers like potatoes. Grain crops 

 may therefore be grown with greater safely on infected soils, than 

 can root crops. 



Freezing;. — The germ survives a freezing temperature. Galtier 

 kept tuberculous matter at different times in a frozen state for 

 four and five days respectively and found it still infecting. Neither 

 the winter's frost, therefore, nor the usual alterations of tempera- 

 ture in the soil can be trusted to speedily disinfect it. 



Putrefaction is not fatal to the germ (Cornil, Babes, Mallassez, 

 Vignal, Galtier, etc.). 



Heavy salting of meats has been thought to be fatal to the germ 

 in one month. After fifteen days in salt the germ failed to kill 

 rabbits but still killed the Guinea pig, whereas after thirty days 

 it killed neither (Galtier). In salting, however, the meat is im- 

 pregnated unequally in different parts of the same mass, and 

 therefore, as in the case of a temporary heating, this cannot be 

 relied on as a safe measure of disinfection. 



The comparative indestructibility of the germ under any of 

 these conditions, shows that the slow absorption of pigments by 

 the bacillus, is significant of an equally tardy penetration by 

 other hurtful agents, and of a corresponding power of resistance 

 to ordinary disinfectant agents. 



Accessory Causes of Tuberculosis. 



While all must to-day recognize that the one essential cause of 

 tuberculosis is the bacillus, yet it is wrong to ignore the fact that 

 many conditions of the animal system and its surroundings con- 

 tribute to the propagation of the disease, or retard its progress. 



