21 

 PLATE XI. 



THE EARTH-WORM continued. 



DISPOSITION OP INTERNAL ORGANS 



FIG. 1 and DIAGRAM 



ALIMENTARY SYSTEM. 



BLOOD SYSTEM CIRCULATORY 

 AND EESPIRATORY . . 



/ Mouth. 



Cut end of muscular pharynx. 

 Gullet, 



Crop, a dilated portion of gullet. 

 Gizzard, whitish, thick, and muscular. 

 Intestine leading straight to anus, and covered with a brownish 



mass supposed to be the liver. 



Colourless corpuscles in perivisceral cavity two shown. 

 Pseud-haemal vessels contractile, and therefore circulatory 



Supra-intestinal vessel (L. supra, above). 



Sub-intestinal vessel (L. sub, under). 



Sub-neural vessel. 



Commissural vessels connecting supra-intestinal and sub- 

 intestinal vessels. 



REPRODUCTIVE SYSTEM . . J 



Dilated commissural vessels in the region of the reproduc- 

 tive organs, the so-called hearts. ' 



Coloured fluid without corpuscles contained in pseud-haemal 

 vessels acts as an oxygen-carrier, and is therefore respira- 

 tory in function. 



RENAL SYSTEM Segmental organs in pairs in each segment. 



/Cerebral or prae-oral ganglia connected by commissural cords 



embracing the pharynx with the 

 NERVOUS SYSTEM . . . . J Sub-cesophageal or post-oral ganglia which form the anterior 



extremity of a 



V Chain of ganglia extending to end of body. 

 Ovaries and oviducts. 

 Testes and vasa deferentia shown in fig. 2. 

 FIGS. 2, 3, 4. RENAL AND REPRODUCTIVE SYSTEMS 



Segmental organs with internal ciliated opening and external pore (tig. 3). 

 ( Anterior pair of spermathecae. 

 ( Posterior pair of spermathecas. 

 ( Anterior pair of bilobed testes. 

 ( Posterior pair of testes. 

 l Anterior reservoir of testes with duct. 

 \ Posterior reservoir of testes with duct. 

 Common vasa deferentia. 



Capsulo-genous glands for secreting egg-capsules. 

 Ovaries. 



Oviducts with wide ciliated internal opening and external opening (fig. 4). 



FIG. 5. Ovary with ova. When laid the eggs are enclosed in clusters within a chitinous case, each egg 

 consisting of Vitelline membrane. 

 Vitellus. 

 Germinal vesicle. 

 Germinal spot. 



Spermatozoa from Spermatheca. 

 CLASSIFICATION 



Sub-Kingdom Annelida (L. annulus, a ring), because the body is segmented ; without jointed 



limbs ; nervous system forms a ring round gullet, followed by a ventral chain of ganglia. 

 Natural Order Oligochse'ta (Gr. oligos, few ; chaite, hair), because the bristles are in rows, not 



tufted. 



Genus Lumbricus. 

 Common Name Earth-worm. 



