both the blood corpuscles and the rods, and such filtered blood was
found to be innocuous. It was further shown that the rods increased
enormously in number in the infected animal, for the blood contained
them in great numbers when but a fraction of a drop was used for
inoculation. Attempts were also made with a greater or less degree of
success to grow the rod shaped organisms or bacilli in various fluids,
and the characteristic disease was produced by inoculating animals
with these cultures; but it remained for Koch, 1878, who was at that
time an obscure young country physician, to show the life history of
the organism and to clear up the obscurity of the disease. Up to that
time, although it had been shown that the rods or bacilli contained in
the blood were living organisms and the cause of the disease, this did
not explain the mode of infection; how the organisms contained in the
blood passed to another animal, why the disease occurred on certain
farms and the adjoining farms, particularly if they lay higher, were
free. Koch showed that in the cultures the organisms grew out into
long interlacing threads, and that in these threads spores which were
very difficult to destroy developed at intervals; that the organisms
grew easily in bouillon, in milk, in blood, and even in an infusion of
hay made by soaking this in water. This explained, what had been an
enigma before, how the fields became sources of infection. The
infection did not spread from animal to animal by contact, but
infection took place from eating grass or hay which contained either
the bacilli or their spores. When a dead animal was skinned on the
field, the bacilli contained in the blood escaped and became mingled
with the various fluids which flowed from the body and in which they
grew and developed spores. It was shown by Pasteur that even when a
carcass was buried the earthworms brought spores developed in the body
to the surface and deposited them in their casts, and in this way also
the fields became infected. From such a spot of infected earth the