CHAPTER XV. 

 PHYLUM V. ANNULATA (SEGMENTED WORMS). 



LABORATORY EXERCISES. 



252. The Earthworm (Allolobophora or Lumbricus). 

 The principal work should be done with living worms. For 

 whatever anatomical work is undertaken, specimens may be 

 killed by exposure to fumes of chloroform while wrapped in 

 cloth moistened with water; they should then be pinned out 

 straight, and hardened in an abundance of alcohol. If needed 

 in the winter they may often be found under manure heaps, 

 or about green-houses. They may be kept alive in flower pots 

 containing moist earth. 



1. Promorphology; General Form. Is there an anterior 

 and a posterior end? How distinguished? Is there any dis- 

 tinction of dorsal and ventral surfaces? If so, what? Is there 

 bilateral symmetry? What external evidences of segmentation 

 do you find? How are the similar units (metameres or seg- 

 ments) arranged? Compare with the condition in the star- 

 fish. Compare the metameres of different parts of the body, 

 noting differences. Is the body divisible into regions (i. e., 

 groups of similar metameres) ? Locate (by numbering the 

 segments) all such regions. How many segments in the ani- 

 mal? To what extent does this vary in different specimens? 

 Show by a series of diagrams the shape of the animal, and 

 the shape and size of cross sections in various regions. 



2. Activities. Describe, after careful observation, the 

 method of locomotion in the earthworm. Place the worm on 

 a rough board: on a plate of glass. What is the difference? 

 And why? Compare the various parts of the body as to size, 

 during movement. Cause of the difference? Can each end 

 move foremost? What seems to determine which end shall 

 protrude as the result of the muscular contractions? 



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