FIXING AND HARDKN1NG AGENTS. 43 



Kecent authors find the action of this liquid to be identical 

 with that of plain bichromate, and doubt whether the 

 sulphate in it has any effect whatever as regards its harden- 

 ing properties. Fol says that for mammalian embryos, for 

 which it has been recommended, it is worthless. 



54. ERLICKI'S Solution (Warschaiter med. Zeit., xxii, Nos. 15 

 and 18; Progrcs Medical, 1897, No. 31). 



Bichromate of potash . . 2'5 parts. 



Sulphate of copper . . I'O part. 



Water . . . 10OO parts. 



Here the addition of the cupric sulphate is intelligible, for 

 this salt is itself a hardening agent of some energy. As a 

 matter of fact, " Erlicki ' hardens very much more rapidly 

 than either simple bichromate or Muller's solution. A spinal 

 cord may be hardened in it in four days at the temperature 

 of an incubator, and in ten days at the normal temperature 

 (FoL, Lclirb. d. vcrgl. mik. Anat., p. 106). Human embryos 

 of several months may be conveniently hardened in it. 



Nerve-centres that "have been hardened in Erlicki's fluid frequently 

 contain dark spots~with irregular prolongations, simulating ganglion- 

 cells. These are now known to consist of precipitates formed by the 

 fluid. They may be removed by washing with hot water, or with water 

 slightly acidified with hydrochloric acid, or by treating the specimens 

 with 0'5 per cent, chromic acid before putting them into alcohol 

 (TSCHISCH, Virchow's Arch., Bd. xcvii, p. 173 ; EDINGEE, Zeit. wiss. Mile., 

 ii, p. 245 ; LOEWENTHAL, Rev. med. de la Suisse romande, 6me annee, 

 i, p. 20). 



55. KULTSCHITZKY'S Solution (Zeit wiss. Mik., iv, 1887. p. 348). A 

 saturated solution of bichromate of potash and sulphate of copper in 

 50 per cent, alcohol, to which is added at the instant of using a little 

 acetic acid, five or six drops per 100 c.c. 



To make the solution, add the finely powdered salts to the alcohol in 

 excess, and leave them together in total darkness, for twenty-four hours. 



Fix for twelve to twenty-four hours in the dark. Then treat with 

 strong alcohol for twelve to twenty-four hours. 



56. Dekhuyzen's Liquids (C. -B. Acad. Sci., cxxxvii, 1903, pp. 415 

 and 445). (A) 250 c.c. of 2'5 per cent. sol. of bichromate in sea-water, 

 25 c.c. of 6'3 per cent, nitric acid, and 54 c.c. of 2 per cent, osniic acid. 

 For general use with marine animals. 



(B) 1731 c.c. of the bichromate sol. and 26'9 of 2 per cent. sol. of 

 osniic acid. For objects containing calcareous elements that it is desired 

 to preserve. 



These liquids are stated to be isotonic with sea-water. 



