GENERAL BIOLOGY 



IV. REPRODUCTIVE SYSTEM. 



1. Seminal vesicles (for storage of own sperm) ; composed of 

 3 pairs of white sacs arising from a median portion below the 

 oesophagus. This median portion is subdivided into an anterior 

 and a posterior part. 



2. Seminal receptacles (for receiving sperm from another 

 worm) ; 2 light colored sacs on the ventral surface of the body- 

 wall, on each side of the median line and attached to septa be- 

 tween the 9th and loth and nth somites. 



3. Ovaries ; very small light colored bodies with pointed tips 

 and rounded bases on the anterior wall of the I3th somite, not 

 very far from the middle of the ventral surface, one on each side, 

 right and left. 



4. Oviducts ; these are also not easily seen, but form what ap- 

 pear as thickenings of the wall between I3th and I4th somites. 



5. Cut off the lateral lobe of a seminal vesicle, cut open its 

 median part and carefully wash out its soft contents to show the 

 following structures ; great care in dissection and observation is 

 necessary, (a) Vasa Efferentia; large folded or convoluted masses 

 which form the funnel-like openings, one on each side of the 

 median line in the loth and nth somites. From these, delicate 

 thread-like ducts pass back on each side to unite in somite 12 to 

 form the Vas Deferens, which passes along the body wall one on 

 each side of the median line, as far back as somite 15 where it 

 opens to the exterior, (b) Testes; four small white bodies, a 

 pair in each somite, inside the seminal vesicles in part concealed 

 by the funnels of the vasa efferentia, and attached to the posterior 

 surfaces of the septa between somites 9 and 10, and 10 and n, 

 two on the right and two on the left of the median line. 



Make a sketch of the reproductive system and explain the func- 

 tion of each part. 



V. NERVOUS SYSTEM. 



1. The nerve cord; extending the whole length of body on the 

 median ventral line, lying in the body cavity but near the body wall. 

 In each somite it expands to form a ganglion and gives off three 

 pairs of nerves, (a) Two large pairs arise from the ganglion, 

 (b) One smaller pair arises from the slender part of the cord 

 (connective) near the anterior end of the somite. 



2. Circum-oesophageal nerve ring. Raise the oesophagus and 



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