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R. KOCH. 
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orable arrangement for the dispersion of the sputum particles than the rapid 
drying on cloth, from which with every motion little threads separate them¬ 
selves, which carry the infectious material into the air, remain suspended 
comparatively long, and when they finally sink to the ground are whirled up 
again by the lightest breath of air. The investigations of the air carried on 
by Hesse are specially instructive on this subject. 
As has already been mentioned, the virulence of the dried sputum can 
be preserved for months ; under some circumstances perhaps longer. The 
last qualities of the virulence depend probably upon its containing well de¬ 
veloped spores capable of developing germs. In any case, even if the dried 
sputum retains its virulence only a few weeks, a consumptive in the condi¬ 
tion in which one generally finds these sick persons is very well adapted to 
provide his immediate surroundings with abundant quantities of infectious 
material, and, moreover, in the most favorable form for the causing of in¬ 
fection. 
When the tuberculous bacilli are inhaled in dust-form, then they can either 
remain in the upper air passages or force themselves into the alveoli just as is the 
case with other inhaled particles of dust. The depth to which they enter the respi¬ 
ratory tract will depend essentially on the manner of breathing ; if breathed deep 
and with open mouth, they will get in farthest. Breathing through the nose will, 
on the contrary, guaranty a certain protection against the entrance of the bearers 
of the infectious material, since a considerable quantity of dust of the air breathed 
is retained by the mucous membrane of the nose. But whether the tuberculous 
bacilli, when they reach the bronchii and alveoli, are able to take firm hold and 
establish themselves will depend on many circumstances. Especial influence on 
this will be exercised by the slow growth of the tuberculous bacilli. Other disease- 
producing bacteria, for example the anthrax bacteria, appear in consequence of 
their rapid growth to grow very soon to such an extent and to exercise so quickly 
a harmful influence on the cells in their neighborhood, that the ciliated epithelium 
of the mucous membrane of respiration is no longer able to master and dispose of 
them ; they can on that account establish themselves in the upper sections of the 
respiratory passages and call forth the pathological processes peculiar to them. 
This is taught by the wool sorters’ disease and especially the affection running its 
course under the term of anthrax of the larynx. Quite different are the relations 
for tuberculous bacilli. These need as many days as the anthrax bacilli hours to 
reach a development worth mentioning, and before they reach it are in ordinary 
circumstances usually ejected by ciliary motion of the epithelium long before this. 
Therefore specially favorable moments must come to make their establishment 
possible. These are certainly brought about by many conditions. Nevertheless, 
the most important and most frequent helps for the establishment of the infection 
appear to be furnished by such diseases as, for example the measles, for a time rob 
the mucous membrane of respiration of its protecting epithelium, or which furnish 
stagnating secretions in which the tuberculous bacilli can establish themselves. 
Also, and that correctly, attention has been called to the fact, that by adhesions 
of the lungs and imperfect form of the thorax, which hinder a sufficient movement 
of the lungs and which are especially adapted to cause circumscribed collections 
of bronchial secretions, the arising of tuberculosis, that is the establishment of 
