STAINS AND STAINING 53 



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 from 5 to 30 minutes. Since there is 

 no danger from precipitates and the solution does not overstain, 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, eryth- 

 rosin, or orange G are good contrast stains. Jeffrey uses safranin and 

 ErHch's haematoxylin for woody tissues. 



Boehmer's haematoxylin. — 



j Haematoxylin 1 g. 



\ Absolute alcohol 12 c.c. 



f Alum 1 g. 



\ Distilled water 240 c.c. 



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

 add about 10 drops of A to 10 c.c. of B. Stain from 10 to 20 minutes. 

 Wash in water and proceed as usual. 



Cellulose walls take a deep violet. The closing membrane (torus) of 

 the bordered pits of conifers will usually stain deeply in about 15 min- 

 utes. Lignified, suberized, and cutinized structures stain slightly or 

 not at all. When they do stain, the color is not violet, but a light 

 yellow or brown. 



THE CARMINES 



Botanists have never given the carmines a fair trial, doubtless be- 

 cause the stains were not considered worth it; but the splendid prepa- 

 rations by Professor Powers of various members of the Volvocaceae, 

 and by Belling in staining pollen mother-cells whole, prove that we 

 should pay more attention to this group. Only a few of the multitudi- 

 nous formulas will be considered. 



The carmine solutions keep for several years, some of them even 

 improving with age, if distilled water has been used in the formulas 



