SOME REACTIONS AND ADAPTATIONS 

 AMONG ANIMALS 



PROBLEM XXVII (OPTIONAL) 



The relations of the earthworm to its surroundings. 



Materials. A shallow tray, moist blotting paper, hand lens, ruler, a 

 pasteboard cover to fit tray, bristles, living earthworms. 



a. External Appearance 



Method. Place living worm in the shallow tray on moist blotting 

 paper. 



Observations. 1. Is it an active or sluggish animal ? 



2. What is its general color ? 



3. What advantage to the worm is the relation of its color to the color 

 of the earth ? 



4. What is its general shape ? What is its symmetry ? 



5. How should you identify the anterior end ? 



6. How does the dorsal surface differ from the ventral surface ? On 

 which surface does the worm crawl ? 



7. Find the broad band (girdle} near the anterior end. 

 Conclusions. 1. How distinguish the anterior from posterior end ? 



2. How does the earthworm resemble other animals you have studied ? 

 How does it differ ? 



3. How may it escape its enemies ? 



b. Motions 



Observations. 1. Measure the shortest length and the greatest length 

 of the same worm. 



2. Examine and compare the regions of expansion and contraction as 

 the worm moves forward. 



3. Run your finger lightly over the ventral surface of the worm. What 

 do you feel? (Use specimens preserved either in (1) formalin or (2) 

 alcohol, then dehydrated, then run into xylol, and then dried.) 



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