LEECHES 



mal are fertilized by the sperm cells of another. They lay 

 their eggs in spring and summer, some species continuing to 

 produce them for five or six months at a stretch. The eggs of 

 all leeches except the family GlossiphonidcB are surrounded by a 

 homy capsule or cocoon, sometimes with several eggs in one 

 case, and glued to stones, plants, or trash, or buried in damp 



Fig. 115. — Diagrams of a leech: i, dorsal side 

 showing the eyes, segments numbered above; 2, 

 ventral side showing the mouth opening and the 

 clinging suckers. (From Moore, after Nachtrieb.) 



earth. But the family GlossiphonidcB carry their eggs in cap- 

 sules attached to their ventral sides; there the young ones 

 hatch out and cling to their parent with then- heads hanging 

 free (Fig. 118). 



Leeches are easily recognized. Their habits are well known 

 and their medical use is of such long standing that the phrase 

 "stick like a leech" has been included in the dictionaries. If 

 one only knows one kind of leech it is easy to recognize others. 

 Leeches are nearly all aquatic; only a few live on land. They 

 are curiously varied in their eating habits: a single leech may 

 feast on snail-meat at one meal and suck turtle blood at its 

 next one. Those of the same species will sometimes be found 



149 



