390 METHODS IN PLANT HISTOLOGY 



Osmic acid. — 



Five or six drops of the stock solution to 50 c.c. of water is good for 



unicellular and colonial algae. In many cases 1 or 2 c.c. to 100 c.c. of 



water is better. 



STAINS 



Delafield's haematoxylin. — 



To 100 c.c. of a saturated solution of ammonia alum add, drop by 

 drop, a solution of 1 g. of haematoxylin dissolved in 6 c.c. of absolute 

 alcohol. Expose to air and light for one week. Filter. Add 25 c.c. of 

 glycerin and 25 c.c. of methyl alcohol. Allow to stand until the color 

 is sufficiently dark. Filter and keep in a tightly stoppered bottle. ^ 



The solution should stand for at least 2 months before it is ready for 

 using. 



Erlich's haematoxylin. — 



Distilled water 50 c.c. 



Absolute alcohol 50 c.c. 



Glycerin 50 c.c. 



Glacial acetic acid 5 c.c. 



Haematoxylin 1 g- 



Alum in excess. 

 Keep it in a dark place until the color becomes a deep red. If well 

 stoppered, it will keep indefinitely. 



Boehmer's haematoxylin. — 



Haematoxylin 1 g- 



\ Absolute alcohol 12 c.c. 



( Alum 1 g- 



\ Distilled water 240 c.c. 



The solution A must ripen for 2 months. When wanted for use, add 

 about 10 drops of A to 10 c.c. of B. Stain 10-20 minutes. Wash in 

 water and proceed as usual. 



Mayer's haem-alum. — 



Haematoxylin, 1 g., dissolved with heat in 50 c.c. of 95 per cent 

 alcohol and added to a solution of 50 g. of alum in a liter of distilled 

 water. Allow the mixture to cool and settle; filter; add a crystal of 

 thymol to preserve from mold (Lee) . 



It is ready for use as soon as made up. Unless attacked by mold, it 

 keeps indefinitely. 



1 Stirling and Lee. 



