272 CHAPTER XX. 



This medium has been frequently recommended as having the property 

 of preventing the blackening of objects that have been treated with osmium; 

 but it seems extremely doubtful whether this is really the case. 



400. Chloral Hydrate. 5 per cent, in water (LADOWSKY, 

 Arch. f. mik. Anat., 1876, p. 359). 



Or, 2'5 per cent, in water (BEADY, British Copepods). 

 Or, 1 per cent, in water (MuNsoN, Journ. Roy. Mic. Soc., 

 1881, p. 847). 



401. Alcohol. Not recoinmeiidable for mounting, as if 

 taken weak it is not an efficient preservative, and if taken 

 strong it attacks the cement of mounts. 



The chief use of alcohol for preservation purposes is of 

 course for preserving specimens in till wanted for further 

 preparation and study. See on this point the remarks in 

 Chap. I, 3. 



402. Formaldehyde. See 104. 



Mercurial Liquids. 



(I give these as examination media only, not as permanent mounting media. 

 Media containing sublimate always end by making tissues granular.) 



403. GILSON'S Fluid (CARNOY'S Biologie cellulaire, p. 94). 

 Alcohol of 60 per cent. . . .60 c.c. 



Water 30 



Glycerin 30 



Acetic' acid (15 parts of the glacial 



to 85 of water) . . . . 2 ,, 



Bichloride . . . . 0'15 grm. 



A really excellent examination medium for the study of 

 fine cellular detail with well-fixed objects. 



404. GAGK'S Albumen Fluid (Zeit. f. wiss. Mile., 1886, 

 p. 223). 



White of egg . . . .15 c.c. 



Water 200 



Corrosive sublimate . . . 0'5 grm. 



Salt ...... 4 grms. 



