246 MACERATION, DIGESTION, AND CORROSION. 



i, 1884, p. 349) takes equal parts of 10 per cent, solution of bichro- 

 mate of potash and visceral fluid of the animal. 



524. Permanganate of Potash is recommended, either alone or 

 combined with alum, as the best dissociating agent for the fibres of 

 the cornea (KOLLETT, Strieker's Handbuch, p. 1108). I have found 

 it, for some objects, very energetic. 



525. 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 taken for a cube of 5 millimetres of 

 the tissue (RANVIER). 



526. Osmic and Acetic Acid (the HERTWIGS, Das Nervensystem 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 



Medusce are to be treated with this mixture for two or three 

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

 of 0-1 per cent, acetic acid until all traces of free osmic acid are 

 removed ; they then remain for a day in 0*1 per cent, acetic acid, 

 are washed in water, stained in BE ALE'S carmine, and preserved in 

 glycerin. 



For Actinice the osmic acid is taken weaker, 0-04 per cent. ; 

 both the solutions are made with sea water ; and the washing out 

 is done with 0-2 per cent, acetic acid. If the maceration is complete, 

 stain with picro-carmine ; if not, with BEALE'S carmine. 



527. MOBIUS'S Media (Morph. Jahrb., xii, 1887, p. 174). 



1. One part of sea water with 4 to 6 parts of 0-4 per cent, solution of 

 bichromate of potash. 



2. 0-25 per cent, chromic acid, 0-1 per cent, osmic acid, 0-1 per cent, 

 acetic acid, dissolved in sea water. For Lamellibranchiata. Macerate 

 for several days. 



528. Nitric Acid. Most useful for the maceration of muscle. 

 The strength used is 20 per cent. After twenty-four hours' macera- 

 tion in this, isolated muscle-fibres may generally be obtained by 

 shaking the tissue with water in a test-tube. Preparations may 

 afterwards be washed with water and put up in strong solution of 

 alum, in which they may be preserved for a long time (HOPKINS, 

 Proc. Amer. Soc. of Microscopists, 1890, p. 165). 



Maceration is greatly aided by heat, and at a temperature of 

 40 to 50 C. may be sufficiently complete in an hour (GAGE). 



