254 ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 



animals depends to a very high degree upon the absence of proper ven- 

 tilation and upon proximity to each other. In the open air and wild 

 life it does not seem to occur. It has been well ascertained that the 

 microbes of cattle plague may cling so persistently to infected places 

 that whitewashing, scraping, and ordinary disinfection may be insuffi- 

 cient. Similarly, tuberculosis of cattle occurs again and again in par- 

 ticular stalls, showing that the infective matter remains in a virulent 

 condition on the walls, floor, or ceiling, and probably infects not only 

 by contact, but through air. The breath of the animal condensed on 

 the walls would no doubt form pabulum for the increase of any rem- 

 nants of a former multitude which might light upon them or emerge 

 from the pores of the material. In France, epizootics greatly increased 

 after the introduction of railways, owing to emanations from and con- 

 tact with incompletely disinfected cattle trucks, yards, sheds, etc., and 

 the diffusion of infectious cases by increased movement. 



INSUFFLATION OF ANTHRAX, ETC. 



The inbreathing of the bacilli of cowpox, anthrax, clavelee, and sup- 

 puration is sufficient to give each of these diseases to sheep and cattle. 

 But there is no evidence to show that any animal plague is transmissi- 

 ble through any long distances of air or by the general atmosphere; on 

 the contrary, animals are in thousands of instances kept within a mile 

 or less of others which are stricken, and with due precautions remain 

 well. 



TUBERCULOSIS. 



Many of the epizootic diseases which occur in animals may be trans- 

 mitted to men, but they often occur in a modified form and are either 

 more or less severe. Some may have been originally human maladies. 

 Fifteen at least are said to be thus interchangeable. The most im- 

 portant, widespread, and fatal of these is consumption, phthisis, or 

 tuberculosis. The bacillus tuberculosis kills about 1 in 8 of the 

 population of Great Britain and America, and about an equal propor- 

 tion, one-seventh, according to a very high authority (Hirsch) of the 

 people of the majority of other civilized countries. It is the greatest 

 and most constantly present plague of man. It has been considered 

 ineradicable, constitutional, hereditary, and attributed by many author- 

 ities to some vice in the atmosphere. Now, we know that it is a nation- 

 ally self-inflicted, unnecessary, and preventable pestilence, of which the 

 great and certain prophylactic is pure air in plenty; no foul air, foul 

 dwellings, and overcrowding. Overcrowding, the rebreathingof expired 

 air, dirty, dusty dwellings, moist or organically polluted Avails, floors, 

 ceilings, and furniture, and the careless habit of spitting account for a 

 very large part, perhaps the majority, of cases of consumption. The 

 breath in fetid air, the emanations from cultures of the bacillus on the 

 walls, curtains, carpets, etc., and, most potently, the dust of the dried 



