THE MEDICINAL LEECH 



feeding, the velum is drawn back to allow the jaws to be pushed 

 forward into the cavity of the sucker and pressed onto the skin of 

 the host. Each jaw is a muscular ridge shaped like half a circular 



Position of jaws- 



Pharynx- 

 Radial muscles- 



Crop - 



Dorsal sinus- 



Intestine- 



Rectum- 



xz 



XX 



100/ 



Broin 



.Sub-oesophageoi 

 S ganglion 



Bladder of 

 nephridium 



^CL 



^' 



u 



(f<o 



Penis sac 



Ovary 

 Vagina 



Vas deferens 



5 th testis 



Ventral nerve cord 



i6th nephridium 



21 st free ganglion 



(a) (b) 



Fig. 3, (a) dissection of H. medicinalis to show gut. The body 

 wall has been opened by a median dorsal incision and pinned 

 back laterally, (b) dissection to show nephridia, reproductive 

 organs and central nervous system. The gut has been removed 

 and the body wall stretched laterally. 



