200 
It. KOCH. 
all died in the course of two to three weeks after the injection and had grea fc 
quantities of tubercles in lungs, liver and spleen. 
The tuberculous knots generated by injection into the course of the blood, 
like all the other infections brought about by pure cultures, were not to be distin¬ 
guished from the tubercles arising spontaneously. They contained tuberculous 
bacilli in greater or lesser numbers and were virulent, for, when inoculated into 
other animals, as was frequently done, they caused tuberculosis in the same man¬ 
ner as the inoculations with genuine, spontaneous tuberculosis. 
Inhalation of Puee Cultukks of Tuberculous Bacilli. 
In order to bring tuberculous substances into the lungs of animals to be ex¬ 
perimented on, either from a tracheotomic wound an injection was made into the 
bronchise, or the infectious mass suspended in a liquid was made into spray and 
breathed in by the animals. The first method does not sufficiently correspond 
with the natural mode of infection, and is complicated in a disturbing manner 
by the wound necessary for the operation. On that account I have chosen the 
second method, which to be sure, for evident reasons, is not without danger to 
the experimenter, and hence demands especial precautions. 
The experiment was carried out in the following wa} r : a very roomy box 
with an opening on one side for the mouth of the atomizing apparatus, was 
placed in a garden at a sufficient distance from inhabited rooms. The atomizing 
apparatus was put on the outside of the box and projected with its mouth into 
the interior of the box. By means of a rubber and a suitably long lead pipe 
which w 7 as put through the wooden framework of a closed window, the appara¬ 
tus was connected with the rubber bellows, and could so be set in motion from 
the room without the necessity of the experimenter’s venturing within reach of 
the atomized liquid. 
Twenty-sixth experiment: Pure culture from a human phthisic lung (No. 1) 
cultivated fifteen months in twenty-three successive breedings was rubbed up 
with distilled water and the liquid so thinned that it appeared almost clear. 
What visible crumbs were still present in the liquid were deposited after a short 
rest, and the upper layers of the liquid, showing scarcely any cloudiness, were 
poured off and used for inhalation. On three successive days, each time in the 
course of half an hour 50 cctm. were atomized and inhaled by the following ani¬ 
mals in the box : eight rabbits, ten guinea pigs, four rats, four mice. After the 
inhalation the animals were kept in separate cages, and well taken care of. In 
some animals, in ten days difficulty of breathing showed itself; then three rab¬ 
bits and four guinea pigs died in from fourteen to twenty-five days. All the 
other animals were killed twenty-eight days after the last inhalation. All the 
rabbits and guinea pigs had numerous tubercles in the lungs, varying in size ac¬ 
cording to the length of time the animal had lived after the inhalation. In the 
animals dyiDg latest, in those killed there were already tubercles in the liver and 
spleen. The tubercles in the lungs were in every respect exactly like those which 
were obtained in guinea pigs and rabbits through inhalation of phthisic sputum 
in experiments undertaken for other purposes. Especially the tuberculous knots 
generated by inhalation of phthisic sputum and those generated by the inhalation 
of pure cultures had that in common, that when they had reached a certain size 
