CHAPTER XXIX. 367 



solution with sodium or lithium carbonate, and freshly distil. A 

 20 per cent, solution is then prepared and rendered isotonic : 

 75 gins, of NaCl to 100 c.c. of fluid. With short fixation (thirty-five 

 minutes to five hours), the quantity of fat usually does not differ 

 from that seen in fresh tissue (Bullard). Cut on freezing microtome, 

 stain by one of the methods given below, preferably Herxheimer's 

 alkaline scarlet red. As control use also fresh tissue. 



For quinolein blue, see 322. 



DADDI (Arch. Ital. BioL, xxvi, 1896, p. 413) stains fat in tissues 

 by treating for five to ten minutes with concentrated alcoholic 

 solution of Sudan III. washing for the same time with alcohol, 

 mopping up with blotting paper, and mounting in glycerin. 



Similarly RIEDER, see Zeit. wiss. Mik., xv, 1898, p. 211. 



The alcohol for making the stain should be of 70 per cent., 

 according to most authors, though SATA (Beitr. 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 (Virchoiv's Arch., clxiv, 1901, p. 263) recommends 

 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. HERXHEIMER (Deutsche 

 med. Wochenschr., xxvii, 1901, p. 607 ; Zeit. wiss. 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 solution, and stains in a couple of minutes. 

 Wash out with alcohol of 70 per cent. 



With either solution the staining must be done in a covered vessel 

 or the stain will precipitate. 



Similarly BELL, Amer. Jo-urn. Anat., ix, 1909, p. 401, and Anat. 

 Rec., iv, 1910, p. 199. 



HERXHEIMER also (Centralb. (dig. Path., xiv, 1903, p. 841 ; Zeit. 

 wiss. Mik., xxi, 1904, p. 57) recommends a saturated solution of the 

 dye in a mixture of equal parts of acetone and 70 per cent, alcohol. 



He also (Deutsche med. Wochenschr., xxvii, 1909, p. 607 ; Zeit. 

 wiss. Mik., xix, 1902, p. 67) has had very fine results by staining 

 for 20 minutes in a saturated solution of Indophenol in 70 % 

 alcohol. 



MOLLISON (Zeit. wiss. ZooL, Ixxvii, 1904, p. 529) has had good 

 results by staining gelatin sections for a few minutes in strong 



