216 
G. SEK. 
The respiration of air loaded with the dust of dried sputa is the 
most certain mode of transmission of human phthisis. When 
sputa are coughed up on the ground, they dry and soon mix with 
the dust. When the patient soils his linen handkerchief (which 
he often uses to cleanse his mouth, which is constantly in con¬ 
tact with the virulent matter), there again is formed a kind of dry 
pulverulent dust, and it is known that the bacteria of the air are 
not isolated, in suspension, but that they are there only after the' 
desiccation and the breaking up of the superficial layer of bac- 
tiferous liquid, or when they are carried by a very volatile dust, 
as that coming from vegetable fibres, hairs or epidermic scales, 
as from clothing. This has been demonstrated by Hesse. 
The virulency of these.dried sputa continues for months, de¬ 
pending especially upon the greater or less complete growth of 
the bacilli and the quantity of spores they carry. 
II.—Mode of Entrance Into the Respiratory Part—Numerous 
Obstacles. —When bacilliferous dust is inhaled it may, like other 
kinds, remain in the superior respiratory organs, or progress as 
far as the alveolae, which is the case in deep respiration with the 
mouth open. 
The nostrils already form an obstacle to the entrance into the 
respiratory canals ; the larynx stops them or rejects them during 
coughing ; when they arrive further it is not yet certain that they 
will remain there, as they are often turned back by the vibratory 
epithelium of the bronchiae. As bacilli develop very slowly, they 
need the assistance of concurrent favorable circumstances to 
attach them. A stagnant mucous, for example, easily holds them ; 
or, again, when adhesions of the lungs render it immovable, a 
vicious conformation of the chest produces the same result by 
preventing the entire dilatation of the lung, and so producing 
the accumulation of the exudation in the bronchiae, where the 
bacillus not only fixes itself but readily develops. 
INHALED BACILLIFEROUS LIQUID. 
1.—Experiment of Koch. —The liquid of culture having been 
diluted and allowed to rest, a portion of it deposited, the slightly 
turbid superior layer was decanted and placed in a dose of 0.50 
