APPENDIX II 701 
STAINING AND MountTInG CELLOIDIN SECTIONS 
1. Place sections in safranin solution for 1 day. This safranin 
solution should be made by dissolving as much safranin in 95 per 
cent. alcohol as it will take up and then diluting with an equal 
quantity of water. ' 
2. Rinse sections in.50 per cent. alcohol to remove excess of 
stain. 
3. Transfer them to Delafield’s haematoxylin for 10 minutes 
(Delafield’s haematoxylin is made by dissolving 1 gm. of hama- 
toxylin in 6 cc. of absolute alcohol and adding this gradually to 
100 cc. of a saturated aqueous solution of ammonia alum. This 
is left exposed for a week, filtered, 25 cc. each of methyl alcohol 
and glycerin added, allowed to stand 6 hours, again filtered, and 
ripened about 2 months before using). 
4. Rinse sections thoroughly first in water, then in 35 per 
cent. alcohol, then in 50 per cent. alcohol. 
5. Put them quickly through acid alcohol (1 drop of HCl in 
50 cc. of 70 per cent. alcohol). 
6. Transfer to 70 per cent. alcohol for about 2 minutes. 
7. Transfer to 85 per cent. alcohol for about 2 minutes. 
8. Transfer to 95 per cent. alcohol for about 2 minutes. 
9. Transfer to absolute alcohol for about 2 minutes. 
10. Clear sections in a mixture of equal parts of cedar oil and 
phenol for at least 2 minutes. 
11. Remove excess of clearing solution and mount in balsam. 
12. Label slide. 
DestLiciFICATION OF Harp Woopy MarTeErIALs 
It frequently happens, even after prolonged maceration or 
boiling in alkaline solutions, that thin sections of hard roots, 
stems, woods or fruits are difficult or impossible to procure. 
This is due to the presence of deposits of silica and other mineral 
substances that usually occur in woody tissues. Therefore, it is of 
prime importance that these substances be removed as thoroughly 
as possible. For this purpose a 10 per cent. aqueous solution of 
commercial Hydrofluoric Acid (or stronger solutions up to the 
pure acid for very hard materials) is most useful. Small fruits 
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