[45] INSTRUCTIOKS FOR COLLECTING MOLLUSKS BALL. 



inately is reached. Shaking the mixture is all that is now required to 

 mix the spirit and water, and the jar and its contents are ready for the 

 reception of the materials treated with Miiller's fluid. 



The precautions given in the first paragraph of these directions in. 

 regard to the use and abuse of alcohol are vital, and no amount of 

 after treatment of valuable material will atone for the neglect of the 

 precautions recommended for the initial treatment. It is a thousand 

 times better for a collector or a museum to have a little well-preserved 

 material of a given type than bushels of iDoorly preserved material, liter- 

 ally "trash," of the same thing, that drops or breaks to pieces when the 

 anatomist attempts to remove it from the jar. It is better, therefore, 

 for the collector to take infinite pains with a smaller quantity of mate- 

 rial to get it in the right condition with proper preservatives than to 

 endeavor to make up in quantity what his collection may lack in quality. 



As a final precaution, it is strenuously advised that too much mate- 

 rial should never be packed into one jar or vessel to be fixed by a single 

 bath of any given reagent. The volume of the first fixing and preserv- 

 ing reagent should always exceed by several times that of the objects 

 to be fixed or hardened. This excess of the fixing and hardening 

 reagents should be maintained until the hardening is completed. After 

 the fixing and hardening is properly accomplished and the tissues of 

 the objects have been thoroughly fixed and saturated with the reagents, 

 then, and then only, may objects be packed together tightly with a rela- 

 tively small amount of strong alcohol round them : otherwise, maceration 

 may occur. In fixing and saturating large objects, especially if they 

 contain large cavities, these should be opened and filled with the first 

 fixing and hardening reagents by means of a cheap syringe made of 

 .glass, metal, or rubber. 



The permanent preservative to be used after any of the hardening or 

 fixing agents that are commended above should be 70 to 80 per cent alco- 

 liol, which is made by diluting ordinary 95 per cent alcohol with from 

 four-tenths to about one-quarter of its own volume of water. Careful 

 washing of the materials fixed and hardened in bichromate of potash 

 or chromic acid is always to be enjoined before the objects are placed 

 in the permanent preservative. This requires from twenty-four to forty- 

 eight hours, according to the size of the specimens. Very small objects 

 can be washed free from chromic acid or bichromate in a few hours by 

 frequent changing or renewing the water over them. For large objects, 

 over an inch in diameter, washing in a gentle current of water for 

 twenty-four to forty-eight hours is advised before placing permanently 

 in alcohol. When large gastropods are preserved in the shell and 

 intended for anatomical examination, it is very necessary to admit the 

 alcohol to the upper part of the spire by making a small hole with a file 

 or other instrument in one of the upper whorls. Otherwise the delicate 

 organs in this region can not be reached by the preservative fluid. 



