OECIN. 103 



to bring about a double-stain in conjunction with carmine. Though it has - 

 no selective preference for nuclei or protoplasm, it possesses to a high degree 

 the property of imparting different hues and intensity of stain to different 

 tissues ; and the nuclei being brought out by carmine, preparations are ob- 

 tained of a diagrammatic clearness that is not afforded by carmine alone. 



Indigo-carmine is found in commerce. The reader who may desire to 

 prepare it himself will find the necessary directions in Arch. f. mik. Anat., 

 x, 1874, p. 32, and in Journ. Roy. Hie. Soc., ii, 1879, p. 614. 



191. Thiersch's Oxalic Acid Indigo-carmine (see Arch.f. mik. Anat., 

 i, 1865, p. 150). 



192. Tincture of Saffron (H. BLAxc,Zool.Anzeig., 129, 1883, p. 23). 

 Dissolve 5 grammes of saffron in 15 c.c. of absolute alcohol ; allow the 

 solution to settle for a few days, filter, and dilute with one half of water. 

 After staining wash out to the desired degree with 80 per cent, alcohol, then 

 dehydrate with absolute alcohol, and mount in balsam. 



LEVEN (The Microscope, ix, 1889, p. 88 ; Journ. Roy. Hie. Soc., 1889, 

 p. 467) has lately been using saffron for the study of the regeneration of 

 muscle. He stains in a solution containing saffron, 1 part ; absolute 

 alcohol, 100 parts ; water, 200, and washes out in acidulated alcohol (0*5 

 per cent. HC1). Karyokinetic figures dark red, muscle nuclei pale with 

 dark red nucleoli. Leucocytes stain strongly. 



193. Orchella (Orseille) (WEDL, Arch. f. path. Anat., Ixxiv, p. 

 143 ; Journ. Roy. Mic. Soc., ii, 1879. For an account of this sub- 

 stance vide COOLEY'S Cyclopaedia, sub voce Cf Archil "). French 

 orchella extract, from which the excess of ammonia has been 

 removed by gentle warming in a sand-bath, is poured into a 

 mixture of absolute alcohol 20 c.c., acetic acid (concentrated, 

 of 1'070 sp. gr.) 5 c.c., and water 40 c.c., until a saturated 

 dark red stain is obtained, which must then be filtered once 

 or twice. Sections are washed with water, drained, and 

 treated with the stain. Mount in levulose. A protoplasmic 

 stain, nuclei remaining colourless. Connective-tissue cells 

 stain deeply, the intercellular substance less deeply. Epi- 

 thelia, if horny or calcareous, are not stained. The basic 

 substance of bone and teeth take the stain, and so do ganglion- 

 cells and their processes. 



This colour ought to be useful for double-staining. FOL 

 (Lehrb., p. 192) advises staining for an hour in Wedl's solution, 

 then rinsing with alcohol, and staining in a complementary 

 stain. 



194. Orcin (!SEAEL, Virchow's Archiv, cv, 1886, p. 169 ; Journ. Roy. 

 Mic. Soc., 1887, p. 514). Orcin is a vegetable dye which unites in itself the 



