LEECHES 67 



LEECHES 



Leeches are of considerable medical importance and form 

 valuable museum materials. Their collection requires considerable 

 care. The methods used for their preservation are applicable to 

 other soft-bodied worms. 



Study of leeches is greatly facilitated by properly prepared 

 material and is equally hampered by faulty preparations. The 

 preserved leeches should be straight, moderately extended, and 

 undistorted. They should be well fixed and preserved in fluids 

 strong enough to prevent maceration or softening, but not so 

 strong as to render them overhard and brittle. They are com- 

 pletely ruined by drying, which often happens when collectors 

 are busy with other things. 



As leeches contract excessively and irregularly on contact with 

 irritating preserving fluids, the first step in good preparation is 

 to stupefy or anesthetize them. Many narcotic drugs will ac- 

 complish this, but the best one, if available, is carbon dioxide, 

 found in soda water in siphons or other carbonated waters. Chloro- 

 form or ether fumes, chloral, chlorotone, cocaine hypochlorate (of 

 about 1-1000 strength) , a very weak nicotine or tobacco decoction, 

 magnesium sulphate, alcohol, or very weak acid like lemon juice, 

 added very gradually to water in which the leeches are confined 

 are satisfactory narcotizing agents, and the animals will usually 

 die in them extended. Place the leeches in a small covered 

 vessel or stoppered bottle nearly filled with clean water to 

 prevent escape from the stupefying agent. Leeches are very 

 sensitive to nicotine, and in the field one of the best and simplest 

 methods is to drop a few shreds of smoking tobacco into the 



