PATHOGENIC BACTERIA 



frequent an occurrence, and so necessary, it is well to detail in 

 particular the method of staining. 



Starting with the sputum, we search for little clumps or rolled- 

 up masses; if these are not present, the most solid portions of the 

 mucus are brought with forceps upon a clean cover-glass; very 

 little suffices. With another cover-glass it is pressed and spread 

 out evenly; drawing one glass over the other, we obtain two 

 specimens, and these are put aside or 

 held high over the flame until dry. 



If we desire to examine the speci- 

 men quickly, or make a hurried diag- 

 nosis, we use the rapid method, with 

 hot solutions; otherwise we let it stay 

 in cold solution until the next morn- 

 ing, the advantages of which will be 

 later on described. 



The Rapid Method (B. Franker s 

 Method, Modified by Gobbet}. The 

 principle is to combine with the con- 

 trast stain the decolorizing agent; but 

 the preparations are not permanent; 

 the method, however, is very useful. 



Two solutions are required: one 

 of Ziehl's carbol-fuchsin; the other 

 Gabbet's acid methylene-blue. (See 

 Formula No. x, on p. 33.) 



The cover-glass containing the 

 dried sputum is passed three times 

 through the flame, as described in 

 the general directions. It is then placed in the carbol-fuchsin 

 solution five minutes (cold) , or two minutes in the hot, immedi- 

 ately then transferred to the second solution, the acid blue, 

 where it remains one minute, then washing in water. The 

 preparation is dried between filter-paper, and mounted best 

 first in water. Examined with oil-immersion. 



A somewhat longer, but preferable, method is to decolorize 

 the carbol-fuchsin with weaker acid. The smear is treated with 

 8 



Fig. 60. Growth on agar. 



