STAINING, PRACTICAL AND THEORETICAL 



Staining and overstaining in violet. The mixture of these two 

 dyes, however, should be made twenty-four hours before use. 



{e) Better pictures are obtained without a colour filter than 

 with one. 



(/) The sun yellow is used really as an adjunct to the basic 

 Faviol technique. In the basic Faviol technique the use of a 

 yellow filter is recommended as this makes the red-stained (i.e. 

 erythrophile) elements more distinct. In the standard Faviol 

 technique, however, the yellow background imparted by the Sun 

 yellow G affords an excellent contrast for the red-stained, strongly 

 erythrophile elements. 



(g) For further information readers are referred to the authors' 

 original paper, and to pages 76-90 of this book. 



Reference: MacConaill, M. A. & Gurr, E. (1960&, 1961, 1962). 



FEULGEN - NAPHTHOIC ACID HYDRAZIDE 



(A. G. E. Pearse) 



For deoxyribonucleic acid 



Reagents required: 



A. 2-Hydroxy-3-naphthoic acid 



hydrazide o-i gm. 



Alcohol, 50% 100 ml. 



Glacial acetic acid . . . . 5 ml. 



B. Tetrazotized o-dianisidine . . ci gm. 

 Veronal buffer solution, pH 7-4 . . 100 ml. 



Technique: 



1. Take sections down to distilled water, then rinse briefly in 

 N/1 HCl. 



2. Immerse in N/1 HCl at 60° C for the optimum time required 

 for hydrolysis, which is dependent on the fixative used. 



3. Rinse briefly in cold N/1 HCl. 



4. Rinse in distilled water. 



5. Rinse in 50% alcohol. 



6. Immerse for one to three minutes in reagent B at 0° C. 



7. Dehydrate through the usual graded alcohols. 



8. Clear in xylol and mount in D.P.X. 



206 



