88 PATHOGENIC BACTERIA. 



its growth produces acid, Solution B must be added, 

 drop by drop, until i in 16 cm. have been attained, and 

 numerous experiments made to see when the flagella 

 will appear. lyoffler lias fortunately worked out the 

 amounts required for some of the species, and of the 

 more important ones the following amounts of Solutions 

 B and C must be added to 16 c.cm. of Solution A to 

 attain the desired effect : 



Cholera spirillum, ^-i drop of Solution C ; 



Typhoid fever, i c.cm. of Solution B ; 



Bacillus subtilis, 28-30 drops of Solution B ; 



Bacillus of malignant edema, 36-37 drops of Solution B. 



Part of the success of the staining depends upon 

 having the bacteria thinly spread upon the glass, and as 

 free from albuminous and gelatinous materials as possi- 

 ble. The cover-glass must be cleaned most painstakingly : 

 too much heating in fixing must be avoided. After using 

 and washing off the mordant, the preparation should be 

 dried before the application of the anilin-water-fuchsin 

 solution. 



Bunge suggests a mordant consisting of a concentrated 

 aqueous tannin solution and a i : 20 solution of liq. ferri 

 sesquichloridi in water. The best mixture seems to be 

 3 parts of the tannin solution to i part of the diluted 

 iron solution. To 10 c.cm. of this mixture i c.cm. of a 

 concentrated aqueous fuchsin solution is added. It is 

 not necessary to prepare this mordant fresh for each 

 staining, as it seems to improve with age. The use of 

 acid and alkaline solutions added to the mordant is dis- 

 pensed with. 



The bacteria are carefully fixed to the glass, stained 

 with the mordant for five minutes, warming a little to- 

 ward the end, washed, dried, and subsequently colored 

 with carbol-fuchsin warmed a little. 



Bacteria can best be measured by an eye-piece microm- 

 eter. As these instruments vary somewhat in con- 



