68 collector's manual 



water with them, just enough to give the water a very faint 

 tint. The leeches will usually be completely narcotized and 

 relaxed in 30 to 60 minutes. If the decoction is made too strong 

 they will die quickly, contracted. 



When the leeches no longer respond to pinching with a forceps 

 or similar stimulation thej 7- are rapidly drawn between the thumb 

 and fingers to remove the excess mucus and then are laid ex- 

 tended side by side in contact in a flat dish. To keep them in 

 place and to prevent distortion when the fixing fluid is poured 

 on, a piece of muslin or other thin cloth, or of tissue or filter 

 paper moistened with the fluid, may be placed on them. The 

 fixing fluid is then gently poured on, usually at first not quite 

 enough to cover them. This avoids floating and disarrangement. 

 After allowing 10 minutes, or longer for large leeches, for them 

 to harden partially, sufficient fluid is added to immerse them 

 completely, care being taken to prevent floating. For ordinary 

 museum or taxonomic purposes 50 percent alcohol or 2 percent 

 formaldehyde, which can be made by diluting the formalin solu- 

 tion described above (page 63) with an equal quantity of 

 water, will answer perfectly, the latter being preferable as less 

 likely to cause the cuticle to separate. After the fluid has 

 thoroughly penetrated and the leeches have fully stiffened, they 

 are transferred to stronger solutions and finally preserved in 85 

 percent alcohol or 5 percent formaldehyde (the formalin solution 

 described on page 63). They should be placed in wide-mouthed 

 bottles or vials of sufficient length and diameter to keep them 

 straight and to avoid crowding and distortion. Wads of surgical 

 gauze or cheesecloth may be used to hold them in place if 

 necessarv. 



