AIR. 395 



dissemination of such droplets in speaking, coughing, and 

 sneezing, Fliigge had the person under observation intro- 

 duce a suspension of prodigiosus into the mouth. All the 

 observations yielded positive results : The plates exposed 

 at a distance of several meters became covered by char- 

 acteristic colonies, and they remained sterile only after quiet 

 speaking in a low tone. 



With regard to the separation of desiccated germs, it may 

 be said that this may likewise occur frequently. Fliigge 

 found that the movement of the finest dust already begins 

 with a current of air having a velocity of one meter. In 

 the open air the most varied mechanical influences (wagon- 

 wheels, pedestrians) cause the separation of the smallest 

 particles, which are then readily borne by the wind. In 

 rooms particles of dust and fibers are set free by the vibra- 

 tion of the floor, by manipulation of utensils, furniture, 

 clothing, etc. The smallest of these floating particles con- 

 taining germs are, however, as Fliigge has shown, moved 

 in a horizontal direction by minimal currents of air of 0.2 

 mm., and in a vertical direction by currents of from 0.3 to 

 0.4 mm. per second. In the course of his experiments 

 Fliigge succeeded with the prodigiosus in demonstrating 

 the distribution of dust-germs in all possible parts of a 

 closed room. Germ-containing dust is not completely 

 removed from rough surfaces even by the strongest cur- 

 rents of air. Airing of infected clothing, as frequently 

 practised, does not, therefore, entirely attain the object 

 desired. 



Upon the basis of the results of these observations 

 Flugge expresses the view that in the case of all infectious 

 diseases air-infection may take place through the smallest 

 droplets separated from fluid sources of infection. In 

 cholera and typhoid fever this will occur but rarely for in- 

 stance, in the sprinkling of polluted water, in the washing of 

 linen, and the like. The principal role in these affections 

 is played by contact-infection, the dissemination through 

 drinking-water, articles of food, etc. In the infectious dis- 

 eases of the nose, the pharynx, and the respiratory organs, 

 however, the possibility of transmission through small 

 drops must be given greater consideration than it has re- 

 ceived in the past. In diphtheria, influenza, whooping- 

 cough, pneumonia, and pulmonary tuberculosis, droplets 

 containing germs are sent into the air in coughing, 



