BACILLI IN CHRONIC INFECTIOUS DISEASES. 421 



cous membrane, which characterize the disease in the horse, are rarely 

 developed to any great extent. 



In field mice general infection occurs at once as a 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, Loffler 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 



