20 



LEECHES 



of fibres which are anchored beneath the epidermis and penetrate 

 all the previously mentioned layers of muscle. Prominent dorso- 

 ventral muscles are situated between the gut diverticula. 



Botryoidal and vaso-fibroiis tissue 



Between the gut and the muscles of the body wall is found a 

 tissue which is characteristic of jawed leeches and is called 

 botryoidal tissue, from a fancied resemblance in section to bunches 

 of grapes. It consists of a network of very fine capillary channels 

 of the coelomic blood sinus system, lined by swollen globular 

 cells which are heavily laden with brown pigment. The function 

 of these is not fully understood, but they correspond in origin and 



Jaw 



Muscle cells 



Ducts of 

 salivary glands 



Muscle cells 

 cut obllquel 



sverse 

 e cells 



Imm 



Fig. 11. (a) plan of a transverse section through the jaws of 

 Hirudo, (b) details of one jaw in section. 



