610 KEPORT OF COMMISSIONER OF FISH AND FISHERIES. [4] 



With care aud attention an organism as soft as the oyster may be 

 hardened and preserved in common alcohol by gradually increasing the 

 strength of the preservative solution, so that there is little or no per- 

 ceptible shrinkage. The cause of shrinkage is the removal of the water 

 of organization by the alcohol, and, in the case of badly prepared speci- 

 mens, it will usually be found that the first bath of alcohol into which 

 the object was plunged was too strong and had caused the withdrawal 

 of the water of organization much too rapidly and produced an excess- 

 ive shrinkage, much to the injury of the specimen. Some investigators 

 recommend very strong alcohol for the preservation of brains, which it 

 is desirable to harden as rapidly as possible and without distortion. In 

 the case of such soft objects, especially if they are of considerable size, 

 they should be suspended in the preservative fluid by a string attached 

 to the cork, in order that the specimen's own weight may not distort 

 it while the process of hardening is in progress, the distortion being 

 aggravated by any curved or uneven surface upon which such a soft 

 object may rest. 



In the case of comparatively large objects, such as mammals and fishes, 

 the body cavity should be filled with 40 per cent, alcohol by means of a 

 syringe, so as to enable the preservative to act from within as well as 

 from without. In the case of fishes, which are usually thickly covered 

 with slime, especially such species as the eels, hags, and lampreys, the 

 slimy coating should always be washed oft' before immersion in alcohol. 



Dr. Whitman*, speaking of the use of alcohol says : " In the prepara- 

 tion of animals or parts of animals for museums or histological study, 

 it is well known that the chief difficulties are met with in the process of 

 killing. Alcohol, as commonly used for this purpose by collectors, has 

 little more than its convenience to recommend it. Dr. Mayer has called 

 attention to the following disadvantages attending its use in the care of 

 marine animals : 



" (1.) In thick- walled animals, particularly those provided withchitin- 

 ous envelopes, alcohol causes a more or less strong maceration of the 

 internal parts, which often ends in putrefaction. 



" (2.) In the case of smaller Crustacea e.^. Amphipods andlsopods, it 

 gives rise to precipitates in the body fluids, and thus solders the organs 

 together in such a manner as often to defy separation even by experi- 

 enced hands. 



" (3.) It fixes most of the salts of the water adhering to the surface of 

 marine animals, and thus a crust is formed which prevents the penetra- 

 tion of the fluid to the interior.t 



* Methods of Microscopical Research in the Zoological Station in Naples, Am. Nat, 

 XIV, pp. 697-706 and 772-785, 1882. 



tDr. Mayer first noticed this in objects stained with Kleinenberg's haematoxyliu, 

 and afterwards in the use of cochineal, where a gray-gfeeu precipitate is sometimes 

 produced which renders the preparation wortbless. Such results may be avoided by 

 first soaking the objects a few hours in acid alcohol (one to ten parti hydrochloric acic\ 

 to one hundred parts seventy j)er cent, alcohol. ^ 



