AND HOW TO USE IT. 193 



Aqueous Media. — Fresh specimens of minute protophytes can 

 often be very well preserved in — 



(a) Distilled water saturated with camphor. When the 

 preservation of colour is not a special object, about a i-ioth 

 part of alcohol may be added. 



{b) Salycylic acid. Small proportion that will dissolve in cold 

 water is very successful. For coarser structures a stronger solution 

 is preferable ; and this may be made by combining with the acid 

 a small quantity either of borax dissolved in glycerine or of 

 acetate of potash. 



{c) A mixture of i part of glycerine and 2 parts of camphor- 

 water may be used for the preservation of many vegetable 

 structures. 



{d) For preserving soft and delicate marine animals which 

 would be shrivelled up or curled by stronger agents, a mixture of 

 I part of glycerine and i of spirit, with 8 or 10 parts of sea-water, 

 is the most suitable preservative. 



((?) For preserving minute vegetable preparations, the method 

 devised by Hantsch is said to be peculiarly efficient.* 



To Clean Glass Slides and Covers.— First wash well in a 

 solution of soda or potash ; if this does not suffice, use the 

 following : — Bichromate of potash, 2 ounces ; sulphuric acid, 

 3 fluid ounces; water, 25 ounces; and afterwards thoroughly 

 rinse in warm and cold water. 



Dammar Cement.— Dissolve gum dammar in benzole, and 

 add one-third of gold-size ; it dries very quickly, and is preferably 

 used as a fiirst coat for affixing the cover-glass when glycerine is 

 used for mounting. . 



Gum, for attaching labels, covering papers, and objects 

 mounted dry (as parts of insects, foraminifera, etc.). Dissolve 

 2 ounces of gum arable in 2 ounces of water, and add 2 drachms 

 of soaked gelatine (for the solution of which the action of heat is 

 required), 30 drops of glycerine, and a lump of camphor. 



Fluid for the Cultivation of Microscopic Fungi, sufficiendy 

 hygrometric to keep the spores moist, adapted to fungoid growth — 

 Dextrine, 2 grains ; phosphate of soda and ammonia, 2 grains j 



* This formula was given on p. 30. 



