CHAPTER XVI. 187 



(op. ctt.) makes it as follows : 2 gr. of medicinal methylen blue are 

 dissolved in 200 c.c. of water, and 10 c.c. of ^ normal solution of 

 caustic soda added. Boil for a quarter of an hour ; after cooling 

 add 10 c.c. of ^ normal sulphuric acid, and filter. 



Methylenazur is isolated from methylen blue by the prolonged action 

 of an alkali or of silver oxide. It seems also that it is formed in certain 

 mixtures of methylen blue with eosin (KOMANOWSKY, LAVERAN, GTEMSA 

 and others), by means of the eosin, which in these mixtures acts chemi- 

 cally, and can be replaced by resorcin, hydroquinon, and the like. It is 

 best procured from Griibler & Hollborn, who supply it pure as " Azur I," 

 and mixed with an equal quantity of methylen blue as "Azur II." 

 See further as to this dye under " Stains for Blood." See also an 

 important paper by PROWAZEK (Zeit. wiss. Mikr. Tech., 31). 



There are several sorts of methylen blue sold, the most important 

 being- ' methylen blue, according to EHELICH " ; ' methylon 

 blue, according to KOCH"; 'methylen blue BX, according to 

 S. MAYER " ; " Methylenblau, medic, pur." 



The colour to be employed for intra-vitam nerve staining should 

 be as pure as possible. APATHY (Zeit. iviss. Mik., ix, 1893, p. 466) 

 writes that the best in fact, the only one that will give exactly the 

 results described by him is that of E. MERCK, of Darmstadt, 

 described as ' medicinisches Methylenblau." DOGIEL (Encycl. 

 mik. Technik., 1st edition, p. 811) has had his best results with 

 " Methylenblau n. Ehrlich," or " BX," obtained from Griibler & 

 Hollborn. 



338. The Uses of Methylen Blue. As a histological reagent it is 

 used for sections of hardened central nervous tissue, in which it 

 gives a specific stain of medullated nerves. It gives more or less 

 specific stains of the basophilous granulations of " Mastzellen " and 

 plasma-cells, and the granules of NISSL in nerve-cells, also mucin. 

 It is much used in the form of mixtures affording methylen azur- 

 in the study of blood, blood parasites, and similar objects. For all 

 of these see the respective sections in Part II. Further, it stains a 



large number of tissues intra vitam, with little or no interference with 



~ * 



their vital functions. And last, not least, it can be made to furnish 

 stains of nerve tissue, intercellular cement substances, lymph spaces, 

 and the like, that are essentially identical with those furnished by a 

 successful impregnation with gold or silver, and are obtained with 

 greater ease and certainty ; with this difference, however, that gold 

 stains a larger number of the nervous elements that are present in a 

 preparation, sometimes the totality of them ; whilst methylen blue 

 stains only a selection of them, so bringing them more prominently 



