304 BACTERIOLOGY. 



held in the Cornet forceps, covered and kept covered 

 completely with fluid while steamed for two minutes 

 over the flame. 



The Koch-Ehrlich solution decomposes after having 

 been made for a time, so that it must be freshly pre- 

 pared as needed. Solutions older than fourteen days 

 should not be used. The advantages in using ZiehPs 

 carbol-fuchsin solution are that it keeps well and is 

 more convenient for use in small quantities. 



Another method, which is often of value on account 

 of its simplicity and rapidity of performance, is that 

 of Frankel as modified by Gabbett. This consists in 

 staining the cover-glass " smear " with steaming ZiehPs 

 carbol-fuchsin solution for from one to two minutes, 

 and then after washing in water placing it from one- 

 half to one minute directly in a second solution which 

 contains both the acid for decolorizing and the contrast 

 stain. This second solution consists of 



Sulphuric acid . . . . .25 c.c. 

 Methylene-blue in substance . . 2 grammes. 

 Water . . . . . . 75 c.c. 



It is then washed with water and is ready for examina- 

 tion. The tubercle bacilli will remain red as stained by 

 the fuchsin, while all other bacteria will be tinted blue. 

 When the number of tubercle bacilli in sputum is 

 very small they may easily escape detection. Methods 

 have, therefore, been suggested for finding them under 

 these circumstances. Ribbert proposed the addition to 

 the sputum of a 2 per cent, solution of caustic potash 

 and boiling the mixture. The mucus is dissolved, and 

 when the mixture is placed in a conical glass vessel any 

 bacilli present are deposited at the bottom, and may be 

 found in the sediment after removing the supernatant 



