THE EARTHWORM 31 



epidermis of the clitellum is made up of several layers of 

 glandular cells. 



The sacs in which the chsetse are implanted are invagina- 



Fig. 7 



A transverse section through the intestinal region of Lumhr^cus hcrculeus magniiied. 

 Ck, ck, chsetas ; cir. m, layer of circular muscles ; cig; chloragogen cells ; cu, 

 cuticle; d.p, tiorsal pore; e/>, epidermis; {, intestine; /,j/t, longitudinal 

 muscles ; nc^ nerve cord ; n/'k, nephridium ; s^, sub-intestinal blood-vessel, 

 below it are the sub-'neural and lateral neural vessels attached to the nerve cord ; 

 sp, supra-intestinal blood-vessel; iy, typhlosole. 



tions of the epidermis. The cuticle forms a lining to the sac 

 for a certain distance : beyond this the chseta ends in a mass of 

 cells, each one of which can produce a new chajta to replace 

 the old one. Beneath the epidermis is a layer of circular 

 muscle fibres embedded in a granular nucleated substance. 

 The individual muscle fibres are elongate, pointed at both 

 ends, and longitudinally striated. 



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