324 APPENDIX 3 



Put a collodion section in each of 4 porcelain pots with per- 

 forated bottoms (e.g. Gooch crucibles). Put one of the porcelain 

 pots in each of the capsules, A to D. Leave for 15 minutes. Transfer 

 the porcelain pots to distilled water and thus give the sections a 

 preliminary rinse. Remove the sections from the pots and wash 

 them in two lots of distilled water for about 5 minutes altogether. 



Record the intensity of dyeing on an arbitrary scale (maxi- 

 mum + + + + +)• The results will be as follows: — 



A, methylene blue at pH 8 . . • + + + 



-Dj ?j )> )) 3 • * • ' ' ' 



C, eosin Y ,, ,, 8 . . . + 



^y )) )) 5) 3 ■ ' • "T ' T" 



Experiments with gelatine sections. The gelatine sections are used 

 as models of amphoteric tissue-constituents (ground cytoplasm, 

 etc.). 



Repeat the experiment exactly as before, apart from the use of 

 different sections. 



The results will be as follows: — 



A, methylene blue at pH 8 . . -f + -f + + 



B, „ ,, M 3 • o 



C, eosin Y ,, ,, 8 . . o 



D, „ „ „ 3 • • + + + + + 



The effect of acid alcohol on tissues coloured with basic and 



acid dyes 



Fix short lengths of the small intestine of the mouse in Zenker. 

 Embed in paraffin. Cut sections at 8 ^. 

 Solutions required: — 



Basic fuchsine, 0-5% aq. 



Acid fuchsine, 0-5% aq. 



Hydrochloric acid, cone, 1% in 70% ethanol. 



Bring 4 slides to water (through iodine and sodium thiosulphate 

 solutions, as usual after fixatives containing mercuric chloride). 



Put one slide in basic fuchsine solution and another in acid 

 fuchsine solution. Leave for 5 minutes. Rinse with distilled water. 

 Pass through 70% alcohol (5 seconds), 90% (5 seconds), ist abso- 

 lute alcohol (dip), 2nd absolute alcohol (2 minutes), into xylene 

 and then Canada balsam. 



