352 CHAPTER XXI\ f . 



fat is more resistant, but can be removed in a few hours or 

 days by means of oil of turpentine, ether, creosote, xylol, 

 elove oil, of chloroform. See FLEMMING in Zeit. wiss. 

 Mikr., 1889, pp. 39, 178. 



709. Stains for Fat. The simplest, and perhaps tlie best is 

 osmic acid. This stains certain fatty bodies black, but not all. 

 According to ALTMANN, STARKB, and HANDWEUCK, only free 1 

 oleic acid and olein are directly blackened by osmic acid ; 

 stearin and palmitin, and stearic and palmitic acid are only 

 browned by it, with an after-blackening which is produced 

 by subsequent treatment with alcohol. Neither reaction 

 occurs with the 'fatty bodies in the solid state, and can 

 only be obtained when they are either in a state of fusion or 

 solution (from the paper of HANDWERCK in Zeit. iviss. Mik., 

 xv, 1898, p. 177). See also LOISEL, G. R., Soc. Biol, 1903, 

 p. 826. MULON, Zeit. wiss. Mik., xxii, 1905, p. 138 ; GOLODET/, 

 Chem. Rev. Fett. u Harz-Industrie,xvu, 1910, p. 70 (Zeit. wins. 

 Mik., xxviii, 1911, p. 213). 

 For quinolein blue, see 322. 



DADDI (Arch. Ital. Biol., xxvi, 1896, p. 143) stains fat in 

 tissues by treating for 5 to 10 minutes with concentrated 

 alcoholic solution of Sudan III, washing for the same time 

 with alcohol, mopping up with blotting paper, ad mounting 

 in glycerine. 



Similarly HIEDER, see Zeit. iviss. Mikr., xv, 1898, p. 211. 

 The alcohol for making the stain should be of 70 per 

 cent., according to most authors, though SATA (Ueitr. path. 

 Anat., xxviii, 1900, p. 461; Zeit. wiss. Mik., xviii, 1901, p. 

 67) employs 96 per cent. ROSENTHAL (ibid., xix, p. 469 ; 

 Verh. path. Ges., September, 1899, p. 440) insists that the 

 washing-out be done with alcohol of exactly 50 per cent. 



MICHAELIS (Virchow's Arch., clxiv, 1901, p. 263) recom- 

 mends Scharlach R (syn. " Fettponceau "). Stain for fifteen 

 to thirty minutes in a saturated solution in 70 per cent, 

 alcohol, and mount in glycerin or levulose. 



Other authors also commend this stain. UERXHEIMER 

 (Deutsche med. WochenscJir., xxvii, 1901, p. 607 ; Zeit. u'iss. 

 Mik., xix, 1902, p. 66) makes a solution of 70 parts of 

 absolute alcohol, 10 of water, 20 of 10 per cent, caustic 

 soda, and Scharlach R to saturation. This makes a stronger 



