ON MOUNTING OBJECTS. 83 



affinity between the fluid in the cell and the varnish used to seal it 

 permanently. Hundreds of excellent objects have been lost from this 

 cause, and much valuable time and labour thrown away. 



The reason why oil was selected by Mr. Warington for this pur- 

 pose arose from want of action on most crystalline salts, many of which 

 could not be preserved uninjured in any other medium. Castor-oil 

 was chosen in consequence of its not depositing a crystalline stearin 

 by reduction of temperature, as is the case with most oils, and even in 

 some specimens of this material ; it therefore requires to be carefully 

 examined in this respect before it is employed. In the same year I 

 used this medium as a mounting-fluid for minute fungi and pediculi 

 with complete success. 



Mr. Goadby has succeeded in supplying to microscopists a ready, 

 cheap, and effectual means for mounting animal structures with the 

 greatest possible ease and security. The following are his formulae : 



Take for No. 1 solution, bay salt, 4 oz. ; alum, 2 oz. ; corrosive 

 sublimate 2 grains ; boiling-water, 1 quart : mix. For No. 2 solu- 

 tion, bay salt, 4 oz. ; alum, 2 oz. ; corrosive sublimate, 4 grs. ; boiling- 

 water, 2 quarts : mix. 



The No. 1 is too strong for most purposes, and should only be em- 

 ployed where great astringency is needed to give form and support to 

 very delicate structures. No. 2 is best adapted for permanent prepara- 

 tion ; but neither should be used in the preservation of animals con- 

 taining carbonate of lime (all the mollusca), as the alum becomes de- 

 composed, sulphate of lime is precipitated, and the preparation spoiled. 

 For such use the following : 



Bay salt, 8 oz. ; corrosive sublimate, 2 grs. ; water, 1 quart : mix. 



The corrosive sublimate is used to prevent the growth of vegetation 

 in the fluid; but as this salt possesses the property of coagulating 

 albumen, these solutions cannot be used in the preservation of ova, or 

 when it is desired to maintain the transparency of certain tissues, such 

 as the cellular tissue, the white corpuscles of the blood, &c. 



Mr. Goadby's method of making marine-glue for cementing cells 

 is as follows: dissolve separately equal parts of shell-lac and India- 

 rubber in coal or mineral naphtha, and afterwards mix the solutions 

 carefully by the application of heat. It may be rendered thinner by 

 the addition of more naphtha, and is always readily dissolved by 

 naphtha, ether, or solution of potash, when it becomes hard or dry 

 in our stock-pots. 



Professor Quekett's preservative fluid is made of creosote, 1J drs. ; 

 wood naphtha, 3 ounces; distilled water, 32 ounces; chalk, as much as 



