256 ANNULATA 



(4) The crop — about somite 15. (a), (b), (c). 



(5) The gizzard — about somite 17. (a), (b), (c). 



(6) The stomach-intestine — from about somite 17 to end 



of body. 



(a) Shape? 



(b) Size? 



(c) Use? 



(d) Length? 



(e) Diameter? 



(f) Straight or coiled? 



(g) Pouched or straight? 

 (h) Color? 



(i) Contents? 



(j) Typhlosole, or longitudinal ridge in the intestine 

 (a). Shape? 



(7) What is the function of the alimentary canal? 



(8) What is the specific function of each of its parts? Do 



not say "aids digestion," but tell just what part in 

 the work of digestion each organ performs. 

 6. Respiratory System. Respiration is carried on through 

 the whole body surface. The skin is filled with a network of 

 blood-vessels. These vessels take up the necessary oxygen and 

 give off the waste matters to the air. Is the earthworm poikilo- 

 thermal or homoiothermal? Why? 



■ 7. Nervous System. Below the intestines is found the nerve 

 cord. 



(1) Trace it to the posterior end of the body. 



(a) Is it a double or a single cord? 



(b) Do you find a ganglion to each somite? 



(2) Trace it to the anterior end of the body. 



(a) Do you find one or two ganglia to each somite? 



(b) Does the nerve cord continue as a single cord to the 



end of the body? 



(c) If it divides, where? What is the destination of each 



branch? 



(3) Cerebral Ganglia. Look for them on the dorsal side, 



about the second or third somite. Trace their 

 branches. 



