176 WORMS. 



DIAGRAM VIII. 

 The Earthworm. 



The figure named Sect, shows a transverse section of the earthworm ; 

 cut. the cuticle, epid. the epidermis, circ. m. the circular muscles, long, 

 m. the longitudinal museles, b. c. the body-cavity, «. the nerve-cord, 

 gut. the ^t,fold. its infolded dorsal ridge, nef/ir. a nephridium, d. b. v. 

 the dorsal blood-vessel, v. b. m. the ventral or supra-neural blood-vessel, 

 the infra-neural and the lateral-neurals are seen beside the nerve-cord, 

 s. the setEe. (Partly after Lang. ) 



The figure named Hep: shows the reproductive organs ; t. the testes, 

 J. V. the seminal vesicles, v. d. the vas deferens with seminal fiinnels 

 (s. f.\ ffv. the ovaries, o-vid. the oviducts, sp. the spermathecse. The 

 nerve-cord («.) and the septa {s.) are also shown. (Mainly after Vogt 

 and Yung.) 



To the right (Nerv.) is the anterior part of the nervous system, show- 

 ing the brain (*n), the oesophageal ring (r^. ) surrounding the gut, ^. 

 one of the paired ganglia. 



To the left is a diagrammatic nephridium {Nephr.), showing the 

 ciliated funnel (/) and a. septum on which it lies, the non-glandular 

 (». gl.) and the glandular (gl.) parts of the coiled tube, m. the terminal 

 muscular region. 



Below this is a diagrammatic section of the gastrula ( Gast. ), showing 

 the internal hypoblast and the external epiblast cells. 



To the right is a figure (Blasts) of the ventral surface of an embryo, 

 showing some of the superficial ectoderm cells (ect.), the mesoblast {m.), 

 the primary mesoblasts (p. me.), the neuroblasts (nb.), the nephridio- 

 blasts {npr. ). The primary " blasts " in each case are the large terminal 

 cells. (After Wilson.) 



