RESPIRATORY APPARATUS. Ill 



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 

 (fuchsin 1, absolute alcohol 10, carbolic acid 5, aq. dist. 95V and 

 heated repeatedly for about two minutes over a flame. Wash 

 and drain. Gabbet's solution (methylen blue 2, in 100 grammes of 

 a 25% sulphuric acid) is then applied and allowed to remain y 2 

 minute. Wash and examine. 



Fie. 29. 



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Tubercle bacilli. 



Besides the tubercle bacillus, other bacilli (acid-fast), which 

 stain by this method, are found in the feces of cattle and in butter. 



