112 Annual Report for 1893 from the Principal of the 
Anthrax is caused by a comparatively large bacillus, which, on 
account of its size and its constant presence in immense numbers in 
the spleen in every case of the disease, is easy of detection. Fig. 1 
reproduces a photograph of a tiny speck of spleen pulp (magnified 
about 750 times) from a case of anthrax, and in every case of the 
disease microscopic examination of the fresh spleen pulp would show 
substantially the same picture. The bacilli are short, straight, 
motionless cylinders, and while they are here represented under a 
high magnification after staining, in order to show their characteristic 
shape, it may be observed that they are easily recognised in the 
unstained blood when magnified only 300 or 400 times. 
Much has been written regarding the characteristic shape of the 
anthrax bacillus and the means of distinguishing it from other 
organisms, but it may safely be said that, provided the examination 
is made within a few 
hours after death, and 
before the carcass has 
become putrid, there 
is little chance of mis- 
take on the part of 
anyone who has once 
seen a preparation of 
blood or spleen pulp 
from a case of anthrax. 
On the other hand, if 
the'carcass is already 
putrid, the safe rule 
for the veterinary sur- 
geon is to abstain from 
basing his diagnosis on 
the result of a micro- 
scopic examination. 
For this there are two good reasons. The first is, that when putre- 
faction sets in, even in cases other than anthrax, the blood and the 
spleen become invaded by germs that may readily be mistaken 
for anthrax bacilli ; and the second is, that in cases of genuine 
anthrax the bacilli rapidly degenerate as putrefaction proceeds, and 
their presence may thus be overlooked. It was on this latter 
account that a positive opinion could not be given in eleven out 
of the forty-nine cases examined in the Research Laboratory during 
the past year. 
But anthrax in nine cases out of ten can be diagnosed by the 
appearance of the spleen without having recourse to microscopic 
examination. That organ in anthrax — of cattle, at least — is engorged 
with blood, dark in colour, and softened to such a degree that its 
substance will almost flow out when a cut is made into it. When 
this condition of spleen is met with in an animal unexpectedly 
found dead, or that has died after an illness of only a few hours’ 
duration, there is very little risk of error in diagnosing anthrax ; and, 
on the other hand, when the spleen is normal in appearance the 
