138 INTERRELATIONS OF PLANTS AND ANIMALS 



Special Reports 



1. The best aquatic plants. 



2. Life in an aquarium. 

 8. The nitrogen cycle. 



4. The balanced aquarium. 



6. Life in a hay infusion. 



6. Indispensable bacteria. 



7. Animal and plant relations. 



Questions 



1. What is the use of chlorophyll to a plant ? 



2. Where do animals living in water get their oxygen ? 



3. What relations exist between animals and plants in re- 

 gard to food ? 



4. Show in detail what is meant by the ' nitrogen cycle.' 



5. Only how can plants use the free nitrogen of the air ? 



6. What two sorts of bacteria may well be known as in- 

 dispensable? Show why. 



7. What substances are set free when animal tissues decay ? 



8. Show how paramoecia and other one-celled animals may 

 be obtained in the laboratory. 



9. Why do some Protozoa encyst ? 



10. Show why marine Protozoa do not need to encyst. 



11. What are the relations between the animals and plants 

 in a hay infusion ? 



References 



Hunter, Essentials of Biology. Chap. XIV. 

 Elements of Biology. Chap. XII. 



Conn, Agricultural Bacteriology, p. 89. 



Lipman, "Indispensable Bacteria." Everybody's Magazine, August, 

 1909. 



Nevins, G. , " The Balanced Aquarium. " Pearson's Magazine, October, 

 1907. 



Whedon, C. C., " The Fresh-water Aquarium." Country Life in Amer- 

 ica, January, 1905. 



Rogers, J. E., "The Salt-water Aquarium." Country Life in Amer- 

 ica, July, 1904, p. 298. 



