348 



ESSENTIALS OF ZOOLOGY 



deferentia in segment XII. The seminal receptacles are pairs of 

 small white bodies located in segments IX and X. The ovaries are 

 two minute bodies located one on each side of segment XIII. 



Digestive System 



The mouth cavity extends through segments I to III and leads 

 into the bulbous, muscular pharynx which extends through segment 

 V. The pharynx plays the part of a sucker in securing food for 



Fig. 127. — Dorsal dissection of an earthworm in the region of segments I to 

 XXL be, buccal cavity ; eg, calciferous glands ; cr, crop ; dv, dorsal blood vessel ; 

 eo, esophagus ; g, gizzard ; n, nephridium ; sb, subpharyngeal ganglion ; st, intestine ; 

 pe, peristomium ; II-XXL somites; ph, pharynx; p, prostomium. (From White, 

 General Biology, The C. V. Mosby Company.) 



the animal. The esophagus is a straight narrow tube extending from 

 the pharynx through the fourteenth segment. In segments X to XII 

 three pairs of yellow lateral pouches open into it. These are the 

 calciferous glands, the secretions of which help to neutralize the acid 

 organic matter taken as food. The esophagus opens into the ci'op, 



