THE ANIMAL SERIES 395 



QUESTIONS AND EXERCISES 



1. To grow some one-celled animals, place some hay, green grass, 

 or lettuce in water and let it stand at room temperature for a few 

 days. A scum will appear on the suface of the water. This scum is 

 composed of bacteria and one-celled animals. Place a drop of the 

 scum on a microscopic slide and examine. 



2. Dig some earth worms and observe their means of locomotion 

 and their habits. What do they eat? 



3. Examine carefully some house flies, mosquitoes, or other insects 

 and learn their parts and habits. 



4. Look in creeks, ponds, or swamps for crayfish. Of what use 

 are they to man? 



5. Gather some eggs of toads or frogs and watch them develop 

 into animals. Of what value to man are frogs and toads? 



6. In what way are birds and reptiles similar? How are they 

 different? How are birds of more value to man than reptiles? 



7. How has man changed the size and shape of domesticated 

 mammals? Of what value are wild mammals? 



