314 CHAPTER XXIV. 



99 107; RANVIER, Trait'', p. 242). 10 per cent, solution 

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



For vibratile epithelium RANVIER finds the mixture in- 

 ferior to one third alcohol. 



523. Formaldehyde. GAGE recommends the addition of 2 

 parts of formalin (40 per cent, solution of formaldehyde) to 

 1000 parts of normal salt solution. The mixture acts quickly, 

 and yet retards deterioration for some time (quoted from 

 FJSH, Proc. Am. Mir. Soc., xvii, 1895, p. 328). 



524. 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. LAVDOW- 

 SKY (Arcli.f. mil:. Anat., 1876, p. 359) recommends it greatly 

 for salivary glands. HICKSON (Quart. Jourrt. Mic. Sci., 

 1885, p. 244) recommends it for the study of the retina of 

 Arthropods. 



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

 employed strong, 35 to 50 per cent. (MOLESCHOTT) ; so em- 

 ployed they do not greatly alter the forms of cells, whilst 

 weak solutions destroy all the elements. (Weak solutions 

 may, however, be employed for dissociating the cells of epi- 

 dermis, hairs, and nails.) The strong solutions may be em- 

 ployed 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 SCHIEFFERDECKER, Das Mi~ki-i>*l>p, 

 i, 1889, }). 156). See also G-AGE, Proc. Amer. S<>c. <>f M-! <><>- 

 scopists, 1889, p. 35 ; Zeit. f. ids*. Mik., vii, 3, 1890, p. 

 349. 



526. Sulphocyanides of Ammonium and Potassium (STIRLING, 

 Jovni. Anat. and Phyx., xvii, 1883, p. 208). 10 per cent. 

 solution of either of these salts, for epithelium. Macerate 

 small pieces for twenty- four to forty-eight hours. 



527. SOULIER'S Sulphocyanide Mixtures (Travaux de 

 Zool. de Montpellier, Nouv. Ser., 2, 1891, p. 171). SOULIER 



