58 Manual of Veterinary 3Iicrobiology . 



virulent dust, being inhaled by a healthy subject, may 

 determine the outbreak of the disease, this fact hav- 

 ing been established for tuberculosis, charbon, gland- 

 ers, fowl cholera, etc. The experimental injection of 

 microbes within the trachea gives the same result. 



The respiratory mucous membrane, therefore, allows 

 itself to be traversed by microbes. Nevertheless, the 

 presence of pathogenic germs in the air does not im- 

 ply that infection will necessarily take place. These 

 germs are generally deposited upon the mucus of the 

 anterior passages and are then rejected with the prod- 

 ucts of expectoration. The fact that germs are con- 

 stantly absent from the expired air whilst they are 

 always contained in the inspired air, sufficiently shows 

 that the latter is purified in contact with the mucous 

 membrane. 



Absorption by the respiratory mucous membrane 

 may occur throughout its whole extent ; as with other 

 lining membranes, this absorption is favored by solu- 

 tions of continuity. 



Ocular mucous membrane. — The conjunctival mu- 

 cous membrane absorbs certain microbes; of this, 

 accidental inoculation of gonorrhoeal pus in the eye 

 furnishes sufficient evidence. M. Galtier has suc- 

 ceeded in transmitting rabies in this manner. 



Genito-urinary mucous membrane. — Syphilis, gonor- 

 rhoea, in man, and dourine in the horse are generally 

 inoculated by coition in the absence of solutions of 

 continuity either of the vagina or urethra. Fric- 

 tions probably aid in the penetration of the specific 

 germs. Absorption by these intact passages can, 

 therefore, not be doubted. 



The penetration of microbes, therefore, takes place 



