110 METHODS IN PLANT HISTOLOGY 



unnecessary to seal the mounts, which are as hard and durable as 

 those mounted in balsam. 



Material in the thickened Venetian turpentine, when not needed 

 for immediate mounting, may be put into small bottles. The corks 

 should be of the best quahty ; otherwise the turpentine will become too 

 thick. While it can be thinned by adding thin turpentine, it is better, 

 for easy mounting, not to let the turpentine become too thick. If the 

 turpentine is only a little too thick, warming it gently will thin it 

 enough for making mounts; but if any material is to be put away, a 

 few drops of absolute alcohol or of a thin Venetian turpentine should 

 be added. Material in Venetian turpentine, well corked and kept in 

 the dark, does not fade or deteriorate in any way. 



Phloxine and anilin blue. — Fix in chromo-acetic acid and wash 

 in water, as described in the previous schedule. Transfer from 

 water to 10 per cent glycerin and allow the glycerin to concentrate. 

 It is not necessary to use an exsiccator since there is no danger from 

 moisture in the air. When the glycerin attains the consistency of pure 

 glycerin, wash the glycerin out with 95 per cent alcohol. This washing 

 must be very thorough; otherwise the staining will not be satisfactory. 



1. Stain in phloxine. A double stain in Magdala red and anilin blue has 

 sometimes given very satisfactory results; but, just as often, has been entirely 

 worthless. The reason for the discrepancy seems to be that stains sold under 

 the name of Magdala red are of various composition, some of them containing 

 no Magdala red at all. The standardized stain, phloxine, seems to be identical 

 with successful lots of Magdala red and results are rather uniformly successful. 



Make a 1 per cent solution of phloxine in 90 per cent alcohol and stain for 

 24 hours. 



2. Rinse the material for a minute in 90 per cent alcohol. 



3. Stain in anilin blue, using a 1 per cent solution in 90 per cent alcohol. 

 We prefer to make a fresh solution every time we have anything to stain. It 

 is not necessary to measure it. A little of the powder — about half the bulk of 

 a grain of wheat— in 30 c.c. of 90 per cent alcohol, will give an efficient solu- 

 tion. The time required for successful staining will vary from 3 to 30 minutes. 

 Do not put all the material into the anilin blue at once, but, by trying a few 

 filaments at a time, find out what the probable periods may be. 



4. Rinse off the stain in 90 per cent alcohol, and then treat for a few seconds 

 in acid alcohol (1 very small drop of HCl to 30 c.c. of 90 per cent alcohol). The 

 acid alcohol fixes and brightens the anilin blue, but extracts the phloxine. If 

 the anilin blue or the acid alcohol acts for too short a time, the blue will be 

 weak; if they act too long, the red is lost entirely. If the blue overstains too 



