40 W. H. E M I G 



soluble in water that the sections are dehydrated as quickly as pos- 

 sible after a direct transfer from the stain to 95 per cent alcohol. 

 The brick red of stained fungi changes to dull brown if sections are 

 left too long in xylene before mounting. Acids precipitate this 

 dye from solution and change the color from red to blue ; for that 

 reason Congo Red is sometimes used as an indicator. Instead of 

 Congo Red use Direct Fast Scarlet 4BS on either animal or plant 

 tissues. 



375. Congo Corinth G, Erie Garnet B is a direct dye, light 4. 

 This dye is more orange and more fugitive than Congo Red. 



387. Erie Violet BW (NAC) is an acid dye, light 2 to 3; i 

 gram in 100 ml. of distilled water and 1 ml. of 1 per cent sulfuric 

 acid. In sections of animal tissues Erie Violet BW may be used 

 as a counterstain with either Crocein Scarlet MOO, C. I. No. 252, 

 or Crocein Scarlet 7B, C. I. No. 286. 



On plant tissues the cytoplasm of meristematic cells is stained 

 violet while the nuclei remain uncolored. Storage parenchyma 

 and cells containing resin are colored reddish violet to violet-black. 



394. Erie Violet 3R (NAC) is a direct dye, light 3. This dye 

 is not so good as Erie Violet BW, C. I. No. 387, for staining either 

 animal or plant materials. Parenchyma is generally red to reddish 

 violet with the cell walls violet. 



410. Chrysamine G is an acid dye, light 5. Stained tissues 

 are too fugitive to be of any value. 



415. Pontachrome Orange R (Du Pont) is a direct dye, light 

 5. A neutral stain gives a fugitive orange on paraffin sections of 

 plant tissues. In an alkaline solution, blue-green algae are stained 

 a fugitive bright orange. 



419. Erie Fast Red FD (NAC) is a direct dye, light 3 to 4. 

 All of the color is removed from stained paraffin sections upon 

 washing in water or in 95 per cent alcohol ; in this respect the dye 

 resembles Congo Red. In alkaline solutions blue-green algae are 

 deep red to reddish brown. 



438. Trypan Red is a direct dye, light 4. A bright red is ob- 

 tained on plant tissues but the color is not very fast. Trypan Red 

 may be used as a vital stain. 



