58 MANUAL OF BACTERIOLOGY. 



(d) Mount and study in the same. 



2. (a) Cover-glass preparations are made and fixed in 

 the ordinary way. 



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



Saturated alcoholic solution of gentian-violet or fuchsin. 5 c.c. 

 Distilled water 95 c.c. 



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

 crystals. 



(d) Dry and mount in Canada balsam. 



The methods of Hiss are recommended to be used for 

 bacteria that have been cultivated on serum-agar with i per 

 cent. of dextrose. 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 

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

 that of Lofllcr. It is important to use young cultures, pref- 

 erably on agar. 



(a) A small portion of the culture is mixed on a cover- 

 glass with a drop of water. The preparations must be ex- 

 ceedingly thin. The mixing must be done with care in 

 order not to break off the delicate flagella. The cover- 

 glass must be perfectly clean, see page 36. 



(b) 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 5 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 



