EARTHWORM. 



187 



starchy food into sugars, and others— peptic and tryptic — not less im- 

 portant. The wall of the stomach-intestine from without inwards, as 

 may be traced in sections, is made up of pigmented peritoneum, muscles, 

 capillaries, and an internal ciliated epithelium. In the other parts of 

 the gut the innermost lining is not ciliated, but covered with a cuticle. 



Vascular system. — The fluid of the blood is coloured 

 red with haemoglobin, and contains small corpuscles. Along 

 the median dorsal line of the gut a prominent blood vessel 



s.n.v 



Fig. 82. — Transverse section of earthworm. — After Claparede. 



t.., Cuticle ; e.. epidermis ; cm., circular muscles ; l.m., longitudinal, 

 muscles ; s., a seta ; ca., coelom ; j'.c, yellow cells ; 7\, typhlo- 

 sole; v.v., supra-neural .blood vessel ; s.n.v., sub-neural vessel; 

 d.v., dorsal vessel. ( 



extends, another (supra-neural) runs along the upper surface 

 of the nerve-cord, another (infra-neural) along the under 

 surface, while two small latero-neurals pass along each side 

 of this same cord. All these longitudinal vessels, of which 

 the first three are most important, are parallel with one 

 another ; the first three meet in an anterior network on the 

 pharynx ; the dorsal and the supra-neural are linked together 



