50 MANUAL OF BACTERIOLOGY. 



(b) Use the following stain, heated till it steams: 



Saturated alcoholic solution of gentian-violet or fuchsin . s c.c. 



Distilled water . . 95 ^.c. 



(c) Wash in 20 per cent, solution of cupric sulphate. 



(d) Dry and mount in Canada balsam. 



The methods of Hiss are recommended to be used for bac- 

 teria that have been cultivated on media containing blood- 

 serum. They have shown that many streptococci have 

 capsules. The writer has had good success from the latter 

 method, with preparations of the pneumococcus from animal 

 tissues. 



Staining of Flagella. — ^Flagella are among the most diffi- 

 cult of all objects to stain. The best-known method is that of 

 Loffler. It is important to use young cultures, preferably the 

 cloudy water in an agar culture, or a fresh beef -broth culture. 



{a) Spread a small portion of the culture on a cover-glass using 

 a drop of water if necessary. The preparations must be ex- 

 ceedingly thin. The spreading must be done with care in order 

 not to break off the delicate flagella. It is better to allow the 

 drop of culture to run of its own accord over the cover-glass, 

 and not stir it with the platinum needle more than is absolutely 

 necessary. The cover-glass must be perfectly clean (see 

 page 25). 



(6) After drying, fixation is effected by passing through the 

 flame three times. 



(c) The essential point in this method is the use of a mordant 

 as follows : 



Tannic acid, 20 per cent, solution. . 10 c.c. 



Saturated solution of ferrous sulphate . . . S c.c. 



Saturated alcoholic solution of fuchsin. i c.c. 



This solution is filtered and a few drops are placed on the 

 cover-glass, or the cover-glass is placed, face down, in a dish 



