48 Methods in Plant Histology 



walls and also starch and chromatophores stain lightly or not at all. 

 Whenever you are in doubt as to the selection of a stain for general 

 purposes, we should advise the use of Delafield's haematoxylin. 



Mayer's Haem-Alum. Haematoxylin, 1 g., dissolved with gentle 

 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. Transfer to the stain from water. It is seldom 

 necessary to stain for more than 10 minutes, and 4 or 5 minutes is 

 generally long enough. As a rule, better results are secured by 

 diluting the stain (about 1 c.c. to 10 c.c. of distilled water) and 

 allowing it to act for 10 hours or over night. 



This is a good stain for the nuclei of filamentous algae and fungi, 

 since it has little or no effect upon cell walls or plastids. Wash 

 thoroughly in water and transfer to 10 per cent glycerin. Specimens 

 may be mounted in Venetian turpentine, as described in chap. viii. 



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. Transfer to the stain from 

 50 per cent or 35 per cent alcohol. Stain 5 to 30 minutes. Since 

 there is no danger from precipitates and the solution does not over- 

 stain, it is not necessary to treat with water or with acid alcohol, but 

 the slide may be transferred from the stain to 70 per cent alcohol. 

 Eosin, erythrosin, or orange G are good contrast stains. Jeffrey 

 uses safranin and Erlich's haematoxylin for woody tissues. 



Boehmer's Haematoxylin.- 



f Haematoxj'lin 1 g. 



L \ Absolute alcohol 12 c.c. 



f Alum 1 g. 



B \ Distilled water. . 240 c.c. 



