284 MACERATION AND DIGESTION.' 



526. Salt Solution. 10 per cent, solution of sodium chloride 

 is a well-known and valuable macerating medium. 



527. MOLESCHOTT and Piso BORME'S Sodium Chloride and 

 Alcohol (MOLESCHOTT'S Untersuchungen zur Naturlehre, xi, pp. 

 99107; RANVIER, Traite, p. 242). 10 per cent, solution of 

 sodium chloride, 5 volumes ; absolute alcohol, 1 volume. 



For vibratile epithelium, Ranvier finds the mixture inferior 

 to one-third alcohol. 



528. Chloral Hydrate. In not too strong solution, from 2 to 

 5 per cent., for instance, chloral hydrate is a mild macerating 

 agent that admirably preserves delicate elements. LA.VDOWSKY 

 (Arch. f. mik. Anat., 1876, p. 359) recommends it greatly 

 for salivary glands. HICKSON (Quart. Journ. Mic. Sci., 1885, 

 p. 244) recommends it for the study of the retina of 

 Arthropods. 



529. Caustic Potash, Caustic Soda. These solutions must be 

 employed strong, 35 to 50 per cent. (Moleschott) : so employed 

 they do not greatly alter the forms of cells, whilst weak solu- 

 tions destroy all the elements. (Weak solutions may, how- 

 ever, be employed for dissociating the cells of epidermis, 

 hairs, and nails.) The strong solutions may be employed by 

 simply treating the tissues with them on the slide. To make 

 permanent preparations, the alkali should be neutralised by 

 adding acetic acid, which forms with caustic potash acetate 

 of potash, a well-known mounting medium (see BEHRENS, 

 KOSSEL, and SCHIEPFERDECKER, Das Mikroskop, i, 1889, p. 156). 

 It has been found by S. H. and S. P. GAGE (Proc. Amer. Soc. 

 of Microscopists, 1889, p. 35; Zeit.f. wiss. Mik., vii, 3, 1890, 

 p. 349) that instead of acetic acid, 60 per cent, acetate of 

 potash solution, employed in considerable quantity and if 

 desired with addition of 1 per cent, of acetic acid, may be 

 used, the preparations either being mounted therein, or in 

 glycerin or glycerin jelly. They may be stained if the ace- 

 tate be first washed out by treatment for twenty-four hours 

 with alum solution. 



530. Sulphocyanides of Ammonium and Potassium (STIRLING, 

 Journ. Anat. and Phys., xvii, 1883, p. 208). Ten per cent, 

 solution of either of these salts is an admirable dissociating 

 medium for epithelium. Macerate small pieces for twenty- 



