58 Methods in Plant Histology 



lignified membranes nor for staining chromosomes. Methyl green 

 has long been a favorite stain for living tissues. It is more easily 

 controlled than iodine green, especially in double staining to differ- 

 entiate lignified and cellulose walls. 



Acid Green. Make a solution according to the general formula, 

 or simply make a 1 per cent solution in water. This stains cellulose 

 walls and achromatic structures, but scarcely affects lignified walls or 

 chromosomes. 



Anilin Blue. Strong alcoholic solutions are best for botanical 

 work. Even though the dry stain may be intended for aqueous 

 solution, make a 1 per cent solution in 85 or 95 per cent alcohol. 



This stain can be recommended for cellulose walls, achromatic 

 structures of mitotic figures, for cilia, and it is particularly valuable 

 for algae. Directions for using it with algae are given in chap. viii. 



Orange G. Make a 1 per cent solution in water, in 95 per cent 

 alcohol, or in clove oil. We prefer the solution in clove oil. 



Transfer to the aqueous stain from water; to the alcoholic stain 

 from 85 per cent alcohol, since the stain is always applied as a second 

 or third stain; use the solution in clove oil after the dehydration in 

 absolute alcohol. Times are always short and are to be reckoned in 

 seconds rather than in minutes. If the solution in clove oil has 

 been used, rinse it off with pure clove oil and then transfer to xylol 

 before mounting in balsam. 



This is a plasma stain. It is distinctly a general rather than a 

 selective stain, but is valuable as a background for other structures 

 which have been stained violet or blue or green. If first came into 

 prominence as the third member of the triple stain, safranin, gentian- 

 violet, orange. 



Gold Orange.- -This stain, which many incorrectly suppose to 

 be the same as orange G, is much more readily soluble in clove oil 

 and stains with much greater rapidity. 



Bismarck Brown. Use a 2 per cent solution in 70 per cent 

 alcohol. 



This is a good stain for cellulose walls, although it is not so precise 

 as haematoxylin. Embryo-sacs stained in one of the carmines are 

 improved by 1 or 2 minutes' staining in Bismarck brown. Material 

 fixed in alcohol stains better than that which has been fixed in reagents 



