in a paper before the Physiological
Society of Berlin, he announced the discovery of the _tubercle
bacillus_. He was able to demonstrate the existence of the germ of
consumption, and to describe its methods of life, as well as the
character of his ravages.

Here then at last was laid bare the true origin of the most fatal
disease which has ever afflicted mankind. He who has not informed
himself with respect to the almost universal prevalence of consumption
among the nations of the earth, or taken note of the mortality from
that dreaded enemy, by which nearly one-sixth of the human race sooner
or later perishes, will not have realized the awful character of this
enemy. To attack such a foe, to force him into a corner, even as
Siegfried did the Grendel in his cavern, was an achievement of which
the greatest of mankind might well be proud.

The discovery of the bacillus of consumption by no means assured the
cure of the disease; but it foretokened the time when a cure would be
found. This prophecy, though it has not yet been clearly fulfilled,
is, in the closing years of the century, in process of fulfillment.
The enemy does not readily yield; but such has been the gain in the
contest that already within the last twenty years the mortality from
consumption of the lungs has fallen off more than forty per cent! Much
of this gain has been made by the reviving confidence of human beings
that sooner or later tuberculosis would be destroyed. Hygiene has done
its part; and other circumstances have conduced to the same result.
Though neither Dr. Koch nor any other man living has been able as yet
positively to meet and vanquish consumption in open battle, yet the
goblin has in a measure been robbed of his terrors. He is no longer
boastful and victorious over the human race.

After the discovery of the tubercle bacillus, the fame of Robert Koch
became world-wide. In the following year he was made a privy
councilor, and was placed in charge of an expedition organized by the
German government to go into Egypt and India for the investigation of
the causes of Asiatic cholera. The expedition was engaged in this work
for nearly a year. Koch pursued his usual careful method of scientific
experimentation. He exposed himself to the contagion of cholera, but
his science and fine constitution stood him well in hand, and he
returned unharmed.

It was in May of 1884 that he was able to announce the discovery of
the _coma bacillus_, that is