EXPERIMENTS ON DYEING 323 



Dissolve the dyes that are to be tested at 0-5% in buffer solution 

 A diluted with an equal volume of distilled water. Orange G, 

 methyl blue, and aniline blue WS are particularly suitable. 



Add one of the dye solutions to each of the tubes. This is best 

 done with a pipette. If the solution slips down between the agar 

 gel and the glass, discard the tube. Note the time. 



Note the distance to which the dyes have penetrated after the 

 lapse of suitable periods (e.g. 12, 24, and 48 hours). 



The results of this experiment are recorded on p. 237. 



The effect of alkalinity and acidity on dyeing zcith basic and 



acid dyes 



The following are required : — 



methylene blue, o-i% aqueous 



eosin Y, o-i% aqueous 



boric acid/NaOH buffer at pH 8 



boric acid, 0-2 M ... 



NaOH, 0-2 N . 



distilled water .... 



100 ml 



8 ml 



up to I 1. 



acetic acid at pH 3 



Make up 100 ml of 33% w/v acetic acid to 1000 ml with 

 distilled water. 



4 30jLt collodion sections not containing any tissue, washed in 

 distilled water. Any kind of nitrocellulose used for em- 

 bedding in microtechnique is suitable. 



4 40/X gelatine sections not containing any tissue ; washed in 

 distilled water. 



Experiments with collodion sections. The collodion sections are 

 used to represent the acidic tissue-components (DNA, etc.). 

 Put the following in four glass capsules labelled A to D : — • 



