154 
K. KOCH. 
level base—so-called Erlenmeyer alembics—and only so much liquid put into the 
alembic as that the bottom be covered from one half to at most the depth of a cen¬ 
timeter. Tne meat-infusion always remained clear, but in the course of four or five 
weeks a fine-grained sand-like looking white layer formed at the bottom of the vessel. 
The single little grains, which had probably grown from the scarcely visible par¬ 
ticles of the sowed substance, consisted exclusively of tuberculous bacilli. 
If one compares this conduct of the cultures in liquid nourishing media, 
namely their slow growth and the constant clearness of the liquid, with the reports 
of former culture attempts from Klebs, Schiiller, Toussaint (who noticed after from 
one to three days a cloudiness of the culture-liquid) one cannot resist the convic¬ 
tion that these cultures could not have been reinculturen. 
Also in regard to the meat-infusion the phenomenon is repeated, that the flesh 
of various animals and even of such as are only slightly susceptible to tuberculosis 
—as dog, cat and domestic mouse—allow the cultures to develop in almost equal 
strength. It is to be mentioned that neutralized meat-infusion stiffened by an ad¬ 
dition of Chinese gelatine, and thereby changed into a firm breeding ground, which 
can be exposed to the breeding temperature without becoming liquid, also gives 
a breeding ground for tuberculous bacilli cultures. This is, to be sure, considerably 
inferior to the stiffened blood serum, because on the slippery surface the bacilli can 
not be spread out well, and in consequence of this the characteristic membranous 
cultures are not developed, but instead compact, irregular masses. Since some 
disease-producing bacteria—for example inflammation-of-the-spleen bacilli, typhus 
bacilli, glanders bacilli and erysipelas micrococci—grow very vigorously on veget¬ 
able substances—for example especially on boiled potatoes—attempts were made 
in this direction with tuberculous bacilli also, but they have led to no positive results. 
All in all, therefore, no great scope is offered the tuberculous bacilli in regard to 
breeding ground. 
There are similar limitations with regard to a second condition essential for 
the existence of bacteria, with the limits of temperature within which growth takes 
place. 
In often repeated attempts it resulted that in a temperature of 42° C. in the 
course of three weeks no growth took place. Further, in 30° C. the development 
is very slight and ceases completely between 28° and 29° C. The cultures thrive 
best in a temperature of 37° to 38° C. A considerably wider range of tempera 
lure, within which they can increase, stands at the disposal of other disease-pro 
ducing bacteria. The inflammation-of-the-spleen bacilli, for example, grow very 
luxuriantly between 20° and 24° C., and form spores in a short time. They can 
thrive also up to 43° 0. If we take into consideration that the anthrax-bacilli can 
run the entire course of their development to spore formation in twenty-four to 
forty-eight hours, in a temperature which in summer is often reached by the surface 
of the ground, and that they can do this on dead vegetable substrata, the supposi¬ 
tion is justified that they can run their course of development in suitable places 
out of doors and independently of the animal body. No further explanation is 
necessary to show that, owing to this, the aetiology of anthrax takes an altogether 
different shape than if the anthrax-bacilli in their existence were dependent alone 
upon the animal body. The same would hold good of the tuberculous bacilli, if 
they could grow on breeding substrata sqch as occur iu pature and if they could. 
