196 EXAMINATION AND PRESERVATION MEDIA. 



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

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

 1881, p. 847). 



362. Alcohol. Not very recominendable for mounting, as if taken weak 

 it is not a veiy efficient preservative, and if taken strong it attacks the 

 cement of mounts. 



CAEPENTER (The Microscope) recommends a strength of 1 part to 5 of 

 water. 



The chief use of alcohol for preservation purposes is of course 

 for preserving specimens in till wanted for further preparation 

 and study. KULTSCIIITZKY has lately pointed out (Zeit.f. wiss. 

 Mik., iv, 3, 1887, p. 349) that alcohol is not without some 

 defects for this purpose. It alters the structure of tissues by 

 continuously dehydrating their albuminoids, and Kultschitzky 

 therefore proposes for preservation some substance that has 

 not this action, such as ether, toluol, or xylol. After fixation 

 and washing out with alcohol, objects may be put up in one 

 of these till wanted. 



Mercurial Liquids. 



363. Corrosive Sublimate Solution (HAETING'S FLUID, Micro. Diet., 

 Art. "Preservation," p. 640). One part of sublimate to from 200 to 500 of 

 water. (For blood-corpuscles of frog 1400, of birds 1 300, of mammals 

 1 200.) " Harting recommends this as the best preservative for the cor- 

 puscles of the blood, nerve, muscular fibre, &c." 



364. Pacini's Fluids (Journ. de Mic., iv, 1880 ; Journ. Roy. Mic. Soc., 

 (N.S.), ii, 1882, p. 702). Pacini remarks that " bichloride of mercury coagu- 

 lates and precipitates the albuminous matter that exists in the interstitial 

 fluids of the tissues," and therefore in order to prevent this coagulation it is 

 well to associate with it salt for certain preparations, or acetic acid for others. 

 On this principle are prepared the following classical fluids of Goadby and 

 Pacini. 



FLUID No. 1 is identical with that of Harting given above, viz. 1'200 

 sublimate in water. Pacini uses it for removing, when desired, the salt or 

 acid from preparations that have been placed in one of the other solutions. 

 FLUID No. 2 



Bichloride of mercury . . 1 part. 



Common salt 2 



Water ... .... 200 



Of general employment, but especially useful for blood-corpuscles of cold- 

 blooded animals, as it has a less density than the following fluid. It pre- 

 serves spermatic fluid, epithelia, nerves, and muscle-fibres. It is also used 

 for fixing Infusoria, a small quantity being added to the water containing 

 them. 



