MACKRATiON, DIGESTION", AND CORROSION. 273 



Small pieces of tissue are macerated for one to tliree, or 

 even four to five daySj in the liquid, then brought for twenty- 

 four hours into ammonia carmine diluted with one volume of 

 the macerating liquid. 



Gierke pai-ticularly recommends this liquid for all sorts of 

 macerations, but especially for the central nervous system, 

 for which he finds it superior to all other agents. It is also 

 recommended for the same purpose by Nansen (v. Zeit. loiss. 

 Mih, Y, 1888, p. 242). 



531. Bichromate of Potash. — 0'2 per cent. 



BisiG {Fauna u. Flora Golf. Neapel, 16 Monog., 1887^ 

 p. 297) macerates Capitellidee in 0'5 to 1 per cent, solution 

 for months or years, a little thymol being added against 

 mould. 



MuUer's Solution, diluted to same strength, or combined 

 with saliva, has also been used. 



Brock (for nervous system of Mollusca, Intern. Monatssch. 

 Altai., i, 1884, p. 349) takes equal parts of 10 per cent, 

 solution of bichromate of potash and visceral fluid of the 

 animal. 



532. Permanganate of Potash. — Is recommended, either 

 alone or combined with alum, as the best dissociating agent 

 for the fibres of the cornea (Rollett, Strieker's Handbuch, 

 p. 1108). I have found it, for some objects, very energetic. 



533. Chromic Acid. — Generally employed of a strength of 

 about 0'02 per cent. Specially useful for nerve tissues and 

 smooth muscle. Twenty-four hours' maceration will suffice 

 for nerve tissue. About 10 c.c. of the solution should be 

 takeu for a cube of 5 mm. of the tissue (Ranvjer). 



534. Osmic and Acetic Acid (the Hektwigs, Das Nerven- 

 sydem u. die Sinnesorgane der Medusen, Leipzig, 1878, and 

 Jen. Zeitschr., xiii, 1879, p. 457). 



0'05 per cent, osmic acid . . 1 part. 



0"2 „ acetic acid . . 1 „ 



Medusse are to be treated with this mixture for two or 

 three minutes, according to size, and then washed in repeated 

 changes of O'l per cent, acetic acid until all traces of free 



18 



