BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [12] 



they should be washed for some iniimtes in fresh or distilled water, as 

 should be done with all animals which have been treated Avith any 

 mixture containing osmium. 



Kleinenberg's liquid^ was one of the first adopted at the Zoological 

 Station for the i)reservation of marine forms. Since it presents the 

 disadvantage of staining the alcohol, even after repeated washings, and 

 of not hardening the animals sufficiently, its use has been given up 

 little by little, until now it is confined to the preparation of histological 

 subjects, with the single exception of Balanoglossus, which is killed 

 with this solution for exhibition as well as for study. 



Lactic acid, in a solution of one in a thousand in sea water, serves 

 well in treating larvse and small gelatinous organisms. 



Hydrochloric^ pyroligneons, and sulphuric acids are used rarely. 



Corrosive sublimate, recommended first by A. Lang, is much used as 

 a fixing agent, because it has the property of jjermeating tissues rapidly 

 and hardening greatly. It is used in concentrated solution in fresh or 

 sea water, either cold or hot. In manipulations with sublimate, metal- 

 lic implements must not be used, because they decompose the solution 

 and stain the preparations. The solution is made, when possible, with 

 hot water for economy of time, and in vessels of glass or porcelain. 

 Care must be exercised to avoid boiling the sublimate in open vessels, 

 and not to inhale the vapors. The hands must not be immersed in the 

 solution if they have on them open cuts or sores. 



All animals which have been prepared with this reagent can be used 

 for histological researches. Corrosive sublimate is also used mixed with 

 acetic or chromic acid or with sulphate of copper. Animals which have 

 been treated with corrosive sublimate must be washed carefully and 

 thoroughly in fresh water before they are placed in alcohol. Add a 

 solution of iodine drop by drop until the alcohol remains permanently 

 colored thereby; this insures the entire removal of crystals of corro- 

 sive sublimate from the substance of the animal. If this precaution is 

 not taken, the mercury will be reduced from the corrosive sublimate 

 and will stain the animal black, forming a black precipitate on the sides 

 and bottom of the vessel. The amount of iodine to be used depends 

 upon the size and character of animal to be treated. 



Bichromate of potassium. — This is used as a 5 per cent solution for 

 slowly hardening gelatinous animals without rendering them too fragile, 

 when it is not i:)ossible to work with chromic acid. On account of tlie 

 troublesome precipitate which forms when objects treated with bichro- 

 mate are transferred to alcohol, the use of this reagent is not recom- 

 mended. For bleaching the preparations before they are put into 

 alcohol, use a few drops of concentrated sulphuric acid. 



Sulphate of copper. — This is used only in solutions from 5 per cent to 

 10 per cent strength, which are made with hot fresh water, and used 



' Kleinenberg's liquid is made by mixing 100 c. c. of a saturated aqueous solution 

 of picric acid with 2 c. c. of concentrated sulphuric acid. Filter and add three vol- 

 umes of distilled water. 



