62 GENERAL BACTERIOLOGY LESSON 



(/) With a fine pipette remove a little of the sediment 

 from the extreme depth of the glass and rub it between 

 two cover-glasses. 



(g) Dry the films in the air and pass them three times 

 through the flame. 



(h) Wash them in a mixture of alcohol and ether (equal 

 parts) for one to three minutes. 



(i) Dry them between filter-paper and again pass them 

 three times through the flame. 



(k) Stain them with carbol fuchsine or carbol gentian- 

 violet, and proceed in the manner described above. 



This is by far the best method for detecting tubercle 

 bacilli. 



If the sputum is watery, pour 100 cc. of it into a flask 

 and add 5 cc. of liquefied carbolic acid, shake for 

 five minutes, and then proceed as above. 



Urine suspected of containing tubercle bacilli must be 

 treated like watery sputum. 



(3) Staining of frozen sections of tuberculous tissues. 

 (i.) Quick Method. 



(a) Place the sections in carbolic acid (5 per cent) for 

 one to two hours. (This may be omitted.) 



(b) Stain them in carbol fuchsine or carbol gentian-violet 

 for two hours in an incubator at 3 8 '5 0. 



(c) Wash a section rapidly in '6 per cent saline solution 

 or in distilled water. 



(d) Now transfer it to 25 per cent hydrochloric acid, 

 and leave it till the colour changes to yellow or brown : a 

 few seconds are sufficient. 



