454 CHAPTER XXXIII. 



Accad. di Sci. di Torino, 1889 to 1892 ; reports in Zeit. f. 

 wiss. Mik., vii, 1, 1890, p. 61 ; and ix, 2, 1892, p. 219 ; also 

 UNNA, ibid., xiii, 1896, p. 42. 



As regards the safranin reaction, it is well to note that it 

 is not obtained with all brands of the dye ; that of Bind- 

 schedler and Busch, in Bale, gives it, whilst safranin of 

 Griibler does not. UNNA employs chiefly his polychromatic 

 methylen blue ( 321, 794). 



The subject has been carefully investigated by PAUL 

 MAYER (Mitth. Zool Stat. Neapel, xii, 2, 1896, p. 303 ; Zeit. 

 f. wiss. Mik., xiii, 1896, p. 38). As regards the hsematem 

 reaction, he finds 



1. If the staining solution contain free acid, or a rela- 

 tively large amount of alum, then as a general rule the 

 secretion of mucus gland cells does not stain in it. 



2. If it contain a relatively small proportion of alum, but 

 a large proportion of hsemateiu, then it stains many sorts of 

 mucus, and at the same time stains chromatin strongly. 



He also finds that mixtures of a relatively large amount 

 of methyl violet and a relatively small amount of methylen 

 blue with a little acetic acid stain nuclei blue, mucus red 

 (p. 314). Unna's methylen blue stains well; the red stain 

 of thionin keeps badly, that of toluidin blue somewhat 

 better. A sharp stain that keeps well in balsam is got by 

 staining for several hours in a concentrated solution of 

 safranin in 30 per cent, alcohol with a very little hydro- 

 chloric acid. Mucus from different sources reacts very 

 differently, and there are certainly several sorts of mucin. 

 At the same time, thionin, safranin, and other colours, 

 quoted by HOYER as specific stains for mucin, stain in the 

 same way substances that are not mucin, e. g. Corpora 

 amylacea, albumin, gum arabic. He gives the following two 

 formulae for mixtures that stain exclusively mucus (the 

 distinction between mucin and mucigen is not taken in his 

 paper) . 



812. MAYER'S Mucicarmine (op. cit., last ). One gramme 

 of carmine is rubbed up in a capsule with 0'5 gramme of 

 aluminium chloride (must be dry, not damp and yellow), 

 and 2 c.c. of distilled water. The capsule is heated over a 

 small flame for two minutes, until the originally light-red 



