ear in teamsters who are employed in handling and carrying
hides. The disease in man is not so fatal as in cattle, for it remains
local for a time at the site of infection, and this local disease can
be successfully treated.

The beginning of our knowledge of the cause dates from 1851, when
small rod-shaped bodies (Fig. 17) were found in the blood of the
affected cattle, and by the work of a number of observers it was
established that these bodies were constantly present. Nothing was
known of their nature; some held that they were living organisms,
others that they were formed in the body as a result of the disease.
Next the causal relation of these bodies with the disease was shown
and in several ways. The disease could be caused in other cattle by
injecting blood containing the rods beneath the skin, certainly no
proof, for the blood might have contained in addition to the rods
something which was the real cause of the disease. Next it was shown
that the blood of the unborn calf of a cow who died of the disease did
not contain the rods, and the disease could not be produced by
inoculating with the calf's blood although the blood of the mother was
infectious. This was a very strong indication that the rods were the
cause; the maternal and foetal blood are separated by a membrane
through which fluids and substances in solution pass; but insoluble
substances, even when very minutely subdivided, do not pass the
membrane. If the cause were a poison in solution, the foetal blood
would have been as toxic as the maternal. The blood of infected cattle
was filtered through filters made of unbaked porcelain and having very
fine pores which allowed only the blood fluid to pass, holding back
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