AETIOLOGY OF TUBERCULOSIS. 
205 
of all men die of phthisis, and that most phthisic patients, at least for some 
weeks, often for months, throw out great cpiantities of sputum in which enor¬ 
mous quantities of spore-bearing tuberculous bacilli are contaiued. Of these 
numberless infectious germs, which are spread everywhere on the ground, on 
articles of clothing, etc., much the greater part perish again, without ever 
finding opportunity to establish themselves anew in a living organism. If 
one farther considers, that according to the experiments of Fischer and Scliill 
already mentioned, the tuberculous bacilli can retain their virulence in a de¬ 
caying sputum for forty-three days, and in dry air sputum for one hundred 
and eighty-six days, then with regard to the great number of tuberculous 
bacilli produced by the phthisically diseased, and to the endurance of the 
bacilli in a damp as well as dry condition, it is easy to see and explain the 
enormous diffusion of the tuberculous virus. 
As to the method in which tuberculous virus is transmitted from the dis¬ 
eased to the healthy no doubt can obtain. In consequence of shocks from 
coughing of the diseased person, little particles are rent from the tough spu¬ 
tum, sent into the air and so dispersed like dust. Now numerous experi¬ 
ments have taught that the inhalation of finely dispersed phthisic sputum 
not only makes those sorts of animals sensitive to tuberculosis, but also those 
capable of resistance tuberculous with absolute certainty. That man should 
be an exception to this is not to be supposed. It may, therefore, be taken 
for granted that when a healthy human being accidentally finds himself in 
the immediate neighborhood of the phthisically diseased, and inhales parti¬ 
cles of sputum sent forth into the air, he can be infected by them. But in¬ 
fection taking place in this manner will probably not occur very often, be¬ 
cause the bits of sputum are usually not so small that they can long remain 
suspended in the air. Far more adapted for infection is, on the contrary, the 
dried sputum, which, owing to the careless way in which the sputum of con¬ 
sumptives is treated, can plainly get into the air in considerable quantities. 
Not only is the sputum spit directly upon the ground, there dried and trod¬ 
den under foot and stirred up in the form of dust, but it often becomes dried 
and made into dust from the bed clothes, articles of clothing and especially 
from handkerchiefs, which are soiled even by the most cleanly patients by 
wiping the mouth after expectorating the dangerous infectious material. The 
experiences which have been gained from the investigation of the air, with 
reference to bacteria capable of development, have taught that the bacteria are 
not suspended in the air in an isolated condition, but that they, with the liquids 
in which they have grown, dry on the surface of objects and only get into the 
air when the dried up mass breaks off in little bits, or when the bearers of the 
dry bacteria liquid themselves are so light that they can be carried away by 
the lightest breath of air. As such easily moved bearers, little bits of dust act 
best, which consist of fragments of plant fibres, animal hair, epidermis scales 
and similar materials. On that account defilement from vegetable tissues and 
animal hairs and bed clothes, clothing and handkerchiefs, when caused by 
phthisic sputum are most to be feared. From spittoons and from the floor 
dried sputum can only be separated in larger particles, which are not easily 
raised up into the air; on the contrary, one can scarcely conceive a more fav- 
