190 METHYLEN BLUE 



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

 10 c.c. of yiy 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 (Romanowsky, Laveran, Giemsa 

 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 Ehrlich " ; " methylen 

 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. xviss. 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. 911) has had his best results with 

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

 Hollborn. 



377. 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 

 stains 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 

 methylenazur — 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 tissues, inter- 

 cellular cement substances, lymph spaces, and the like, that are 

 essentially identical with those furnished by a successful impregna- 

 tion 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 before 

 the eye, and allowing them to be traced for greater distances. 



378. Staining in toto during Life. Small and permeable aquatic 

 organisms may be stained during life by adding to the water in 

 which they are confined enough methylen blue to give it a very 

 light tint. After a time they will be found to be partially stained— 

 that is, it will be found that certain tissues have taken up the 

 colour, others remaining colourless. If now you put back the 



