[13] THE PRESERVATION OF MARINE ANIMALS HOVEY. 



alone or mixed with corrosive sublimate for killing larv;e and delicate 

 animals. The objects which have been treated with this reagent must 

 be washed repeatedly with water or else they will not remain perfectly 

 clear, owing to the formation of crystals within the tissues, which ren- 

 der them opaque. If they afterwards prove to have been washed too 

 little, the objects should be treated several times with an acid. 



Chloral hydrate. — This is used in very weak solution, from 0.1 to 0.2 

 of 1 per cent made fresh iu sea water, for narcotizing several forms 

 before fixing them. This method has the advantage that, if the animal 

 after a certain time does not remain in the condition desired for pres- 

 ervation, it can be replaced in sea water, where it will regain power of 

 motion and continue to live. It is used for killing animals whicli live 

 in the crevices, of a rock, in incrustations of calcareous algae, and 

 among colonies of serpulas and of madrepores. Such must be allowed 

 to remain in the solution from six to twelve hours. It is not necessary 

 to use a fine quality of the drug. 



Cocaine. — A solution of cocaine is made by dissolving 2 grams of the 

 powder in 100 cubic centimeters of 50 per cent alcohol. This is a most 

 excellent narcotizing medium, but its high cost prevents its extensive 

 use. It is the best reagent thus far discovered for the treatment of 

 gastropods. A few drops are carefully distributed over the surface of 

 the water containing the animals, and the operation is repeated until 

 the animals cease to respond to any stimulus. 



Other reagents that are used occasionally are chloroform, ether, and 

 tincture of iodine. 



Mixtures frequently used. 



Alcohol of 70 per cent and chromic acid of 1 per cent in equal parts. 



Alcohol of 50 per cent cubic centimeters. . 100 



Hydrochloric acid (concentrated) do 5 



Alcohol of 35 per cent or of 70 per cent do 100 



Alcoholic tincture of iodine do 2.5 



Alcoholized sea water : 



Sea water do 100 



Absolute alcohol do 5 



Chrom-acetic mixture No. 1 : 



Chromic acid of 1 per cent do 100 



Concentrated acetic acid do 5 



Chrom-acetic mixture No. 2 : 



Chromic acid of 1 per cent do 10 



Concentrated acetic acid do 100 



Chrom-osmic mixture: 



Chromic acid of 1 per cent do 100 



Osmic acid of 1 jier cent do 2 



Chrom- picric mixture : 



Chromic acid of 1 per cent do 50 



Kleinenberg's solution : do 50 



Sulphate of copper, solution of 10 per cent strength do 100 



Corrosive sublimate, saturated solution do 10 



