208 CHAPTER XV. 



With Toluidin Blue I have had some superb stains of chromatin, un- 

 fortunately accompanied by a diffuse staining of cytoplasm. 



MANN (Zeit. /. wiss. Mik., xi, 4, 1894, p. 489) states that he has had 

 good results by staining with it after eosin,thus obtaining a double stain. 



See further as to the micro-chemical properties of this dye, HAERIS, The 

 Philadelphia Medical Journal, May 14th, 1898. It much resembles 

 rnethylen blue. 



JB. Progressive Stains. 



276. As regards the progressive nuclear stains, the reader is 

 reminded that many, if not most, of the basic coal-tar colours give a nuclear 

 stain of greater or less purity if they are used in solutions acidified with 

 acetic acid. Under the present heading, only those are mentioned which give 

 in all respect, alike as regards precision and permanence, simplicity of mani- 

 pulation and other qualities, a really valuable stain. 



277. Methyl Green. This is the most common in commerce 

 of the "Aiilin" greens. It appears to go by the synonyms 

 of Methylanilin green, Grilnpulver, Vert Lumiere, Lichtgrun ; 

 these two last are in reality the name of another colour. 

 When first studied by Calberla, in 1874 (Morphol. Jahrb., in, 

 1887, p. 625), it went by the name of Vert en cristaux. It 

 is commonly met with in commerce under the name of more 

 costly greens, especially under that of Iodine green. It is 

 important not to confuse it with the latter, nor with Aldehyde 

 green (Vert d'Eusebe), nor with the phenylated rosaiiilins, 

 Paris green, and Vert d'AIcali, or Veridine. 



Methyl green is the chloromethylate of zinc and penta- 

 methyl-rosanilin- violet. It is obtained by the action of 

 methyl chloride on methyl violet. The commercial dye 

 always contains unconverted methyl violet as a consequence 

 of defective purification. It is sometimes adulterated with 

 anilin blue (soluble blue) . It is also sometimes adulterated 

 with a green bye-product of the manufacture, the chloride 

 of nona-methyl-para-leukanilin (see BENEDIKT and KNECHT'S 

 Chemistry of the Coal-tar Colours). 



MAYEE (Mitth. Zool. 8 tat. Neapel, xii, 1896, p. 312) says that the presence 

 of the blue impurity can be demonstrated by placing a drop of the solution 

 of the ^dye on filter paper, and holding the green spot over a bottle of 

 ammonia. If the methyl green is pure, the spot will disappear ; if not pure, 

 it will turn violet. He also says that the violet can be easily removed by 



