26 LABORATORY BACTERIOLOGY 



forms, the spores in spore-bearing organisms, and the capsule 

 on certain other species. There is a large number of these 

 special methods, but in this course only one of each will be 

 given. These will be taken up in connection with the study 

 of the bacteria requiring them. 



37. Formulae for staining solutions. The dyes here used 

 are methylene blue, gentian violet, methyl violet, and basic 

 fuchsin. For the other dyes, see text-books. 



ALKALINE METHYLENE BLUE (LOEFFLER) 



Saturated alcoholic solution of methylene blue . 6 cc. 



Caustic potash (i % solution) 0.2 cc. 



Distilled water 20 cc. 



The saturated alcoholic solution of the methylene blue (or 

 of any of the dyes) is prepared by pouring the dye into a clean 

 bottle and filling it about one fourth full. Then fill the bottle 

 with strong (95 % or absolute) alcohol, cork tightly, shake, and 

 allow it to stand for 24 hours. If at the end of that time the 

 dye is entirely dissolved, add more, shake thoroughly, and allow 

 it to stand for another day. Repeat this procedure untiHhere 

 is a permanent sediment of undissolved coloring matter in the 

 bottom of the bottle. Then label. (The saturated solution 

 will be kept in stock in the laboratory.) 



CARBOL FUCHSIN (ZIEHL'S SOLUTION) 



Fuchsin (dry) I gram 



Alcohol (absolute) xocc. 



Carbolic acid (5 % solution) 100 cc. 



Dissolve the fuchsin in the alcohol, after which add the car- 

 bolic acid solution. Instead of using the dry fuchsin and 

 alcohol, 1 1 cc. of a saturated alcoholic solution of fuchsin may 

 be used. 



It is more convenient for each student to prepare the 

 following : 



Saturated alcoholic solution of fuchsin .... 3 cc. 

 Carbolic acid (5% solution) 20 cc. 



