AXIS-CYLINDER AND DEN UNITE STAINS. 427 



More recently (Cinquantenaire Soc. Biol., 1899, p. 514) 

 Golgi puts for some hours or clays into a mixture of equal 

 parts of bichromate of 2 to 3 per cent, and sulphate of 

 copper of 4 to 5 per cent., or into the cupric mixture used 

 for the intra-cellular network, 777. 



GEMELLI (Anat. Anz., xliii, 1913, p. 414) takes a mixture 

 of " acetate of copper (4 per cent.) and bichromate of potash 

 (5 per cent.)." Time not stated. 



817. Formaldehyde for the Rapid Process. STRONG (Anat. 

 Anz., x, 1895, p. 494) finds that formaldehyde can with 

 advantage be substituted for the osmic acid in the osmio- 

 bichromic mixture of GOLGI'S rapid process. He adds from 

 2'5 to 5 per cent, of formalin to the (3*5 to 5 per cent.) 

 bichromate solution. 



The advantage is that the stage of hardening favourable 

 for impregnation lasts longer ; in other words, the formalde- 

 hyde bichromate does not over-harden. 



DUEIG (ibid., p. 659) obtained the best results by means 

 of 3 per cent, bichromate solutions containing 4 to 6 per 

 cent, of formaldehyde, hardening therein for three days, and 

 after silvering for two days putting back into the mixture and 

 proceeding as in Ramon y CajaFs double impregnation 

 process. 



FISH (Proc. Amer. Hie. Soc., xvii, 1895, p. 319) takes : 

 Formalin . . . . . 2 c.c. 



3 per cent, bichromate . . . 100 



leaving the tissues three days in this liquid and three days 

 in the silver nitrate (J per cent.). 



Or, with advantage : 



Liquid of Miiller . . . .100 c.c. 



10 per cent, formalin . . . 2 



1 per cent, osmic acid . . . 1 



ODIER (La Rachicocainisation, Geneve, 1903, p. 27) takes 

 two parts of undiluted formalin, instead of the 10 per cent. 



The formalin and bichromate mixtures should be kept in 

 the dark. It is well only to make them up at the instant of 

 usiiiy them. Odier finds these mixtures afford a more 

 abundant impregnation, with fewer precipitates. 



KOPSCH (Anat. Anz., xi, 1896, p. 727) takes 4 parts of 3'5 

 per cent, bichromate solution, and 1 of commercial formaldc- 



