PRESERVATION. 



[ 635 ] 



PRESERVATION. 



used for preserving animal structures, or- 

 gans, injections, &c. Delicate preparations 

 may be kept in a mixture ot" 1 part of 

 spirit with 5, or even 10, parts of water. 

 iJilute spirit sliould never be used as a pre- 

 serA ative when it can possibly be avoided, 

 on account of its action upon the cements. 

 Methylated spirit is very useful, on account 

 of its cheapness and strengtli ; may be used 

 when diluted in preserving large specimens 

 of animal tissue. 



Creosote water is prepared by filtering a 

 saturated solution of creosote in rectihed 

 spirit, mixed with 20 parts of water. It is 

 recommended for preserving preparations of 

 muscle, cellular tissue, tendon, cartilage, &c. 



Arscnious acid. — A preservative liquid is 

 made of this substance by boiling excess of 

 the acid with water, iilteriug the solution, 

 and adding 2 parts of water. It is a very 

 good preservative of animal tissues. Arse- 

 uite of potash, 1 part dissolved in 100 of 

 water has been found usefid for preserving 

 the primitive nerve-tubes. 



Corrosive siihliniate. — A dilute solution of 

 this substance is useful in the case of the 

 blood-corpuscles, nerve, muscular fibre, &c. 



Salt (^chloride of sodium) and water, 5 gr. 

 to the ounce, was long since recommended 

 for the preservation of tissues, but is not 

 much used, because fungi are apt to grow in 

 it, which might, however, be prevented by 

 satm'ating it with camphor by digestion. 

 Corti has found a tolerably concentrated 

 solution the best preservative for the delicate 

 structures and nerve-cells of the internal 

 ear. Carpenter recommends sea-water, with 

 one tenth part of alcohol and one tenth of 

 glycerine, for preserving the delicate marine 



organisms. 



Carbonate of potash. — 1 part dissolved in 

 from 200 to 500 of distilled water, is a good 

 preservative of the primitive nerve-tubes. 

 Solution of acetate of potash is also useful. 



Glycerine. — This is the most valuable of 

 all liquids for vegetable preparations, which 

 may be closed air-tight or not at pleasure. 

 Dissections covered with a glass may be 

 left in it from day to day, remaining un- 

 changed and always ready for examina- 

 tion. Objects may be mounted in it, as 

 with chloride of calcium. It is one of the 

 most valuable fluids for the preservation 

 and preparation also of animal tissues. 

 Camphor-water and naphtha and water may 

 be added. 



Glycerine and Gum {FarranCs com- 

 pound). — Pure gum-arabic i oz., glycerine 



1 oz., water 1 oz., arsenious acid 1} grain; 

 dissolve the arstiiiious acid in the water, 

 then the gum, without heat, add the gly- 

 cerine, and incorporate with great care to 

 avoid forming bubbles. 



(Jum-ivater (see Cicment.s). — The solu- 

 tion should be very thick, so as to flow with 

 difficulty from the end of a wire. It may 

 be used like balsam, but without heat. The 

 residue is very apt to crack when dry ; this 

 may be prevented by applying a thick coat- 

 ing of varnisli around its margins. 



Chloride of calcium (Calcium, chloride 

 of). — Objects may be mounted in this solu- 

 tion without closing the cell, by pasting 

 two narrow strips of paper transversely upon 

 a slide, leaving a greater interval than the 

 breadth of the object ; the latter is then laid 

 upon the slide, a small quantity of the solu- 

 tion added, and a cover applied. The solu- 

 tion must not touch the paper. The cover 

 may be fLxed to the paper on the slide by 

 tiie electrical cement with balsam and tallow. 

 It is best, however, to close the cell. 



Chloride of zinc. This is an excellent pre- 

 servative of animal tissues for microscopic 

 examination. It exerts a slight coagulating 

 action, but this is not sufficient to seriously 

 impair the peculiarities of the objects, and 

 large portions of all structures which may 

 require to be examined should be kept in it. 

 The ordinary strength is 20 grs. of the fused 

 chloride to the 1 oz. of water. A lump of 

 camphor should be kept floating upon the 

 surface of the solution in the stock-bottle. 



Goadhy's solutions. — These are of three 

 kinds. The first (A) is made with — bay- 

 salt (coarse sea-salt) 4 oz., alum 2 oz., cor- 

 rosive sublimate 2 grains, boihng water 1 

 quart. This is too strong for most pur- 

 poses, and is only to be employed where 

 great astringency is required to give form 

 and support to delicate structures. 



The second (B) is made with — bay-salt 

 4 oz., alum 2 oz., corrosive sublimate 4 gr., 

 water 2 quarts. This is recommended for 

 general use, and as best adapted for perma- 

 nent preparations. Mr. Thwaites uses it for 

 marine Algaj ; but we have found chloride 

 of calcium answer for this purpose, and it is 

 much more secure. Schultze recommends 

 it for preserving Medusce, Echiiiodermata, 

 Annelid larvse, Entomostraca, Diatomacese, 

 Foraminifera, and Polycystina, both the 

 hard and the soft parts, and advises the 

 use of glycerine afterwards to produce 

 transparence. 



When carbonate of lime exists in the 



