CHAPTER XV 

 PHYLUM IX. ANNULATA (SEGMENTED WORMS) 



LABORATORY EXERCISES 



258. The Earthworm (Allolobophora or Lumbricus). The 

 principal work should be done with living worms. For what- 

 ever 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 contain- 

 ing moist earth. 



1. Promorphology; General Form. Is there an anterior and 

 a posterior end ? How distinguished ? Is there any distinction 

 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 segments) ar- 

 ranged? Compare with the condition in the starfish. Com- 

 pare the metameres of different parts of the body, noting differ- 

 ences. 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 animal ? 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 fore- 

 most? What seems to determine which end shall protrude as 

 the result of the muscular contractions ? 



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