BACILLI IN CHRONIC INFECTIOUS DISEASES. 493 
cous membrane, which characterize the disease in the horse, are rarely 
developed to any great extent. 
In field mice general infection occurs at once asa result of the 
subcutaneous injection of a small quantity of a pure culture, and the 
animal dies at the end of three or four days. Upon post-mortem 
examination the principal changes are found in the liver and in the 
greatly enlarged spleen. Scattered through these organs are minute 
gray points which are scarcely visible to the naked eye. In the 
guinea-pig, which succumbs at a later date, these nodules are larger 
and closely resemble miliary tubercles, both macroscopically and 
under the microscope, in stained sections of the tissues. Similar 
nodules are also found in the kidneys and in the lungs; they have a 
decided tendency to undergo purulent degeneration. The bacilli are 
found principally in these nodules, of recent formation, and are com- 
monly associated in groups, as if they had been enclosed in the inte- 
rior of a cell the membranous envelope of which had undergone 
degeneration and disappeared. 
As before remarked, it is not an easy matter to demonstrate the 
bacillus in sections of the tissues containing these nodules, owing to 
the facility with which they lose their color in alcohol and other de- 
colorizing agents. For this reason it will be best to dehydrate sec- 
tions by the use of aniline oil (Weigert’s method) or to resort to 
Kiihne’s method of staining. 
It is also difficult to demonstrate the presence of the bacillus in 
nodules which have undergone purulent degeneration, in the secre- 
tions from the nostrils of horses suffering from glanders, or in the 
pus from the specific ulcers and suppurating glands ; for they are 
present in comparatively small numbers. But the virulent nature of 
these discharges is shown by inoculations into guinea-pigs or mice, 
and it is easier to obtain a pure culture from such virulent material 
by first inoculating a susceptible animal than directly by the plate 
method; for the small number of bacilli present, and their associa- 
tion with other bacteria which develop more rapidly in our culture 
media, make this a very uncertain procedure. For establishing the 
diagnosis of glanders, therefore, Liffler recommends the inoculation 
of guinea-pigs with pus from a suppurating gland or ulcer, or the 
nasal discharge from a suspected animal, rather than a direct attempt 
to demonstrate the presence of the bacillus by staining and culture 
methods. 
The method proposed by Strauss gives more prompt results. 
This consists in the intraperitoneal injection of cultures or of the 
suspected products into the cavity of the abdomen of male guinea- 
pigs. If the glanders bacillus is present the diagnosis may be made 
within three or four days from the infectious process established in 
