THE NEFflRIDIA OP LEECHES. 561 



Clepsine. — Diagram of a nephridium. a. Funnel. h — c. Testis lobe. 

 c — e. Main lobe. From e, through/, to the apex_^, and back through/ 

 to e, runs the recurrent duct ; this then passes through the main lobe to 

 h, where it runs across to the apex g. g—f corresponds to the apical lobe 

 of Hirudo: from / the duct runs across to e, where it re-enters the 

 main lobe ; at A it emerges and passes as efferent duct to /, the external 

 aperture. 



A B, c D, E F, and G H. Sections through the regions so marked, n, «. 

 Nuclei. The section c d is taken a little to the right hand of the 

 line c D. 



Section a b is a cell of the main lobe with its nucleus «, and contains 

 branching ductules ; and in addition to these it surrounds in two places 

 perforated cells containing the duct in two subsequent portions of its 

 course, also showing nuclei, n, n, in their walls. 



Section c d shows two perforated cells in juxtaposition, each containing 

 a portion of the recurrent duct ; the one as it goes to, the other as it 

 comes from, the apex. 



Section e f shows the single perforated cell which contains the duct 

 in that portion of its course. 



Section g h shows the similar but larger cell containing the efferent 

 duct. 



