130 PRINCIPLES OF VETERINARY- SURGERY 



contaminated with germs harbored on the harness. The 

 chief source of entrance is the digestive tract. The micro- 

 organisms are ingested with the food, pass unimpaired 

 through the digestive and absorbent mechanism and lodge 

 in the lungs, where they produce the first lesion. This de- 

 duction has been proven over and over by numerous ex- 

 periments and observations. Nocard's feeding experiments 

 have proven it beyond question. The watering trough and 

 the feed box are found to be the principal habitats of the 

 bacillus mallei in the stable. It is deposited there by the 

 nasal discharge, which in many and many instances may be 

 trivial in quantity, and may entirely escape notice, and yet 

 be capable of depositing an abundance of virulent microbes. 

 The direct inoculation of the lungs through the respiratory 

 tract is not doubted, but it is known to be rare as compared 

 to the alimentary route. 



Immunity. — Mallein, under certain conditions and by re- 

 peated inoculation, will confer an immunity against the 

 disease, but as Law says, "Altogether, attempts to immunize 

 the equine population are not hopeful where it is dense, 

 where they must be kept stabled, where the climate is moist 

 and the glanders is deadly or tends to persist in the chronic 

 form for years in the same animal." The value of the im- 

 munizing agents at our command is strikingly elucidated 

 in these few words. The writer's own experience with the 

 disease in a large city fully confirms them. Mallein is an 

 immunizing agent of some potency when used repeatedly 

 and when suitable hygienic and working conditions are ac- 

 corded the infected and exposed animals. It seems to re- 

 quire the assistance of the resisting forces of the body. 

 Rabe has asserted that single injections will immunize ani- 

 mals. If this is true it applies only to transient passing 

 immunity, that can only be prolonged by subsequent repe- 

 titions of the mallein inoculations. 



