f 



HIRUDO. 



Fig. I20. — Transverse Section through the Leech 

 {Hirudo mediciitalis). (Mainly after Bourne.) 



193 



Crop cut in 

 three places. 

 Botryoidal 



Tissue, 



Dorsal Sinus. 



Dorso- 

 ventral Muscle. 



Bladder of 



Nephri- / 



dium. _/ 



Testis Lobe of 

 Nephridium, 



Nephridium. 

 Was Deferens. 

 Testicular Coelom. 



Ventral Testis. 

 Sinus. 



OF A Leech. 



(After Whitman.) 



On the last annulus of each segment, from segment 6 



to 22 inclusive, there open on the ventro-lateral line 



paired nephridiopores. 



On the first ^nq segments one 



Fig. 121. —Dorsal View of the sense-organs on each side 



OF THE Anterior End ig enlarged into an eye \ thus 



" there are ^-^^ pairs of eyes. In 



T«+ncr,,»«n«+oT^ ^he median ventral 



Integumentary. ,. ^, . , 



Ime the unpaired 



male genital aperture is found in 



segment 10 and the female in 



segment 11. The body is flexible 



and is enveloped in a thin cuticle 



secreted by the simple ectoderm. 



The mouth leads into a sucking 



pharynx^ the walls of which contain 



unicellular salivary glands and can 



Alimentary, be Pulled out by 



radiatmg muscles. 



A short oesophagus connects it with 



This is a thin-walled but spacious sac which 



14 



The small dots are the sense- 

 organs, of which five pairs are 

 large and formed into eyes. 



the crop, 



M. 



