125 



municating by short and sinuous ducts (vasa efferentia) 

 with two longitudinal vasa deferentia which end in two 

 -convoluted tubular epididymes or seminal vesicles. From 

 ach of these a short duct leads into the swollen base of 

 the penis, where the spermatozoa are formed into packets. 

 The female organs are two small ovaries enclosed in 

 globular sacs (situated behind the base of the penis). 

 Leading Tfrom the sacs are two gmall oviducts ; these 



Dorsal sinus 



Crop 



Botryoidal 

 tissue 



Dorso- 

 ventral muscle 



Circular and 

 muscles 



Lateral 

 blood-sinus 



Bladder of 

 nephri- 

 dium 



Testis-lobe of 

 nephridium 



Nephridium 



Nerve 

 cord 



Vas deferens 

 Testicular coelome 



\ 



Ventral Test is 

 sinus 



FIG. 26. Transverse Section of Leech (Hirudo). 

 After BOURNE. 



unite to form a convoluted duct which widens out as the 

 " uterus," opening to the outside. Fertilisation is internal. 

 The eggs are enclosed in a cocoon. Development is direct. 



Explain the Structure of Hirudo as seen in a Transverse 

 Section of the Body. 



The body cavity or coelome is greatly reduced (of. trans. 

 sec. of Lumbricus), its place being almost entirely occupied 

 by the spongy botryoidal tissue. The dorsal sinus, the 

 ventral sinus surrounding the nerve-cord, the sinus en- 

 closing the testis and testis-lobe, the sacs enclosing the 



