Stains and Staining 89 



The stain given below is the basis for about 90 per cent of all bacteri- 

 ological techniques. 



Other Synthetic Nuclear Dyes 



Ziehl's Carbolmagenta: 



Staining solution 



Grind together 1 g of magenta ("basic fuchsin") with 10 ml of 90 per 

 cent alcohol and 10 g of phenol. When this mixture has been reduced to 

 a paste, take 100 ml of water and rinse out the mortar, using 10 suc- 

 cessive 10-ml batches. These batches should be accumulated, left a few 

 hours, and then filtered. 



The use of this stain for bacteria is described on page 202. If it is to 

 be used for staining nuclei in either animal or plant sections, it is necessary 

 only to transfer the section from water to the stain for 10 to 20 min and 

 then to differentiate as long as is required with 1 per cent acetic acid. 



It is sometimes necessary to stain bacteria blue, either as a contrast 

 to the red color produced by Ziehl's solution or in order to differentiate 

 bacteria that have been decolorized. Much the best solution for this pur- 

 pose is: 



Lillie's Ammonium Oxalate Crystal Violet: 



Note: This solution is often called "Hucker's ammonium oxalate crystal 

 violet" or "Hucker-Conn crystal violet." 



Staining solution 



Dissolve 2 g of crystal violet in 20 ml of 95 per cent alcohol. Dissolve 

 separately 0.8 g of ammonium oxalate in 80 ml of distilled water. When 

 both solutions are complete, add the oxalate solution to the dye solution. 



The proportions used here are those given by Lillie. 



The use of this solution in staining bacterial films is described on page 

 199 and its use for the staining of nuclei is identical with the method 

 outlined for Ziehl above. 



PLASMA OR CONTRAST STAINS 



Wholemounts are almost invariably stained in one color only since 

 sufficient nuclear stain usually remains dispersed throughout the plasma 

 to provide adequate visibility. The cytoplasm of sections, however, is 

 usually stained a contrasting color, both to render the nuclei more ap- 

 parent and to emphasize the general structure. Sometimes two or more 

 colors may be employed. Single contrasts are usually perfectly adequate, 

 and the following may be recommended: 



