RESPIRATORY APPARATUS. 105 



Fine foam. When the discharge comes from the smaller 

 bronchi in pulmonary edema and bronchitis, the foam is 

 composed of small air bubbles of equal size. When there is 

 much foam the discharge is white in color. Horses suffering 

 from chronic bronchial catarrh after exercise show a white 

 nasal discharge partially made up of fine foam. 



Fig. 28. Egg of r . ■„. , -iium Tenioides. 



Coarse foam. This is not infrequently unilateral and 

 contains an admixture of food particles. It comes from the 

 mouth and consists in part of saliva. The air bubbles are 

 of unequal size. Coarse foam is symptomatic of paralysis 

 of the pharynx, pharyngitis (fungus poisoning). 



When food particles alone make up the nasal dis- 

 charge, it is a sign that vomiting has taken place. The dis- 

 charge is then not foamy, is of acid reaction and contains no 

 admixtures of exudate. 



A microscopical examination of the nasal 

 discharge is rarely of practical value. It may sometimes be 

 of use to determine the presence of the embryo or egg of 

 Strongylus filaria in the lungs of sheep or of Pentastomum 

 taenioides in the nasal passages of the dog, or in fetid nasal 

 discharge, the elastic fibres. 



The examination for pathogenic micro- 

 organisms yields positive results only in exceptional cases. 

 The tubercle bacilli are one of these exceptions as their char- 

 acteristic way of accepting stains serves to identify them 

 microscopically. 



Microscopical determination of tubercle bacilli. A cover-glass 

 preparation is covered with Ziehl's carbolized-fuchsin solution 



