SUMMARY s;> 



worms, and leeches. All of these worms have more per- 

 fectly organized parts than the sponges and hydroids. 

 The body of the earthworm shows the first steps in tin- 

 formation of definite front, back, and ventral regions. The 

 digestive tube is also specialized into pharynx, esophagus, 

 crop, gizzard, and stomach-intestine ; and the name brain 

 may be given to a slightly enlarged portion of the anterior 

 end of the nerve cord. Small worms of various kinds are 

 numerous in stagnant water. Some live as parasites in 

 man and other animals, causing much suffering and loss 

 of life. The earthworm as a cultivator of the soil has been 

 of inestimable value to man. 



QUESTIONS 



"What kind of animals are called worms ? Is it proper to call " cur- 

 rant worms" worms ? Why not ? What are they ? How do you recog- 

 nize the anterior, posterior, dorsal, and ventral regions ? Compare the 

 grasshopper or some other insect with the worm. Explain how the earth- 

 worm moves ; makes its burrow. Compare the digestive tube with the 

 digestive sac of the hydra. 



REFERENCES 



Darwin, Earthworms and Vegetable Mould. 



Jordan, Kellogg, and Heath, Animal Studies, Chapter VI. 



Sedgwick and Wilson, General Biology. 



