BLOOD AND GLANDS 409 



falls to the bottom as the solution cools, and the fluid is good for 

 four weeks. 0-5 grm. dimethyl-p-phenylen-diamin is dissolved in 

 250 c.c. of distilled water by light shaking, and stored in a brown 

 flask. It is ready for use after twelve to twenty-four hours, 

 and is good for two to three weeks. Before use the solutions 

 are filtered, and are mixed in equal parts in a shallow dish. 

 Sections to be stained are immediately added and are left in for 

 ten to fifteen minutes, the solution being constantly stirred. 

 They are then transferred to distilled water for a short time, and 

 are transferred to Lugol's iodine diluted 1 in 2 for two to three 

 minutes. (Grams iodine is also good.) They are then trans- 

 ferred to distifled water to which a few drops of lithium carbonate 

 have been added, and are left ten to twenty-four hours, until a 

 good blue colour appears. Lastly, they are counterstained with 

 alum carmine in haematoxylin eosin, washed in water, and mounted 

 in glycerolgelatin. By these methods the granules of the 

 neutrophil, eosinophil, and basophile cells are stained a dark blue. 

 The reaction is given by the myelocytes, by the more mature 

 myeloblasts, while young forms contain no enzyme. Lymphocytes, 

 lymphoblasts and plasma cells show no reaction, though cells of 

 the mononuclear series are as a rule faintly positive. It is un- 

 fortunate that the negative staining of early myeloblasts should 

 render the reaction useless as a distinguishing test in many 

 doubtful cases. 



ScHULTZE [Zent. allg. Path., xxviii, 1917, p. 8) employs 1 per 

 cent, solutions of the constituents dissolving the a-naphthol by the 

 addition of caustic potash to the boiling solution. Blood films 

 are first fixed in 40 per cent, formol 1, absolute alcohol 10. 



Shaw Dunn {Journ. Path, and Bad., xv, 1911, p. 120) uses 

 equal parts of 1 per cent, a-naphthol and dimethyl-p-phenylen- 

 diamin, and mounts in water glass, when the staining is good for 

 many weeks. He finds that various phenols may be substituted 

 for a-naphthol and that paraphenylen-diamin also works, in 

 which case the reaction is slower. Other workers vary the 

 proportions of a-naphthol and dimethyl-p-phenylen-diamin and 

 the staining times with equally good results. See also Graff 

 {Ziegl. Beitr., Ixx, 1922, p. 1). The peroxidase test is largely 

 used in the case of blood films for differentiating between cells 

 of the myeloid and lymphoid series since the reagents are more 

 stable and are more readily obtainable. 



Sato and Sekiga Tohoku {Journ. Exper. Med., vii, 1926, p. 3) 

 have published the following method. A benzidene solution is 

 prepared by rubbing 0-2 grm. of benzidene with a few drops of 

 water in a mortar. Two hundred cubic centimetres of water at 

 room temperature are added and the solution filtered. To the 

 filtrate add 4 drops of 3 per cent. HgO^. A fresh, dry blood film is 

 covered with 0-5 per cent, copper sulphate. This is poured off and 



