THE EARTHWORM 31 



epidermis of the clitellum is made up_of several layers of_ 

 glandular cells. 



The sacs in which the chaetae are implanted are invagina- 



Fig. 7 



A transverse section through the intestinal region of Lumbricus herculeus magnified. 

 C/t, c/i, chsetae ; dr. in, layer of circular muscles; clg> chloragogen cells ', cu, 

 cuticle ; d,p, dorsal pore ; e/>, epidermis ; /, intestine ; /,;//, longitudinal 

 muscles ; nc, nerve cord ; ///, nephridium ; sl>, sub-intestinal blood-vessel, 

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

 s/>, supra-intestinal blood-vessel; ty, typhlosole. 



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

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

 cells, each one of which can produce a new cHeta 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. 



