396 CLINICAL BACTERIOLOGY. 



sneezing, and loud talking ; they are set in motion by min- 

 imal currents of air, and in a quiet room can be demon- 

 strated floating in the air for as long as five hours. 



In cases of air-infection through dry particles of dust, 

 only the finest particles, capable of being carried by any 

 movement of air, demand consideration. Only such diseases 

 are transmitted naturally in this way whose exciting agents 

 are still capable of surviving in the dry state. For the 

 acute exanthemata, which have always been considered as 

 diseases due to volatile contagia, such a possibility must be 

 accepted. 



Pulmonary tuberculosis has hitherto been generally 

 accepted as disseminated through inhalation of ejected 

 dried and pulverized sputum containing tubercle-bacilli ; 

 Fliigge opposes this view. Attempts to infect animals 

 through inhalation of dried tuberculous sputum have never 

 quite succeeded ; and, further, the tubercle -bacilli do not 

 appear at all capable of being carried by the finest particles 

 of dust. Fliigge expresses a warning against going to the 

 other extreme of attaching too great importance to the 

 danger of infection through drops of spray or even of con- 

 sidering it the only source of infection. Infection with 

 tuberculosis is dependent upon a large number of factors : 

 upon the environment of the patient, upon the presence 

 of tubercle-bacilli in the saliva, which forms fine droplets 

 much more readily than the viscid sputum proper, and 

 upon other conditions. 



WATER. 



Method of Examination. The water to be examined 

 is collected in sterilized Erlenmeyer flasks, and is investi- 

 gated as speedily as possible. If the examination is deferred 

 for only a few hours, the indifferent saprophytic bacteria 

 that reside in water will have undergone multiplication, and 

 the estimation of the number of water-germs will not yield 

 reliable results. If the specimens of water to be examined 

 are sent from a distance, the water must be forwarded in 

 sterilized flasks, provided with glass stoppers, and packed 

 in ice. In obtaining water for examination care should be 

 taken that the material to be examined has not stagnated 

 in the conduit from the well or spring or other source of 

 supply. For this reason a certain amount of water is first 



