264 NATURE STUDY REVIEW [9:8— Nov.. 1913 



4. Name some of the causes of injury to seed corn. Explain 

 difference between a balanced ratio and nutritive ratio. 



5. What effect has lime on the development of nitrogen fixing 

 bacteria ? 



6. Name at least five effects of good drainage on soil and crops. 



7. What do you understand by the following terms: capillary 

 water; water table; percolation? 



8. Indicate what you consider a good crop rotation for your 

 community. Give reasons. 



1. What is the soil? Sub-soil? Are earthworms a benefit or 

 an injury to the soil? Why? 



2. How do legumes help to keep up the land? What crop 

 rotation is best for the land? 



3. What do you understand you should do to girdle a tree? 

 What would be the result? 



4. Explain the principal features of tree pruning. When and 

 how often should trees be pruned? 



5 . On what fruit does the codling-moth work ? Where does the 

 curculio lay her eggs? When? 



6. Why is com cut in shocks, when ripe? What would you 

 consider a good crop of com in bushels per acre ? 



7. What is a mulch? On what crops are chinch bugs found? 

 How may these bugs be destroyed? 



8. What birds are of greatest value to farmers ? 



At the Stepney nature-study museum many of the tanks are not 

 artificially aerated, but are kept clear and sweet by the balance 

 between the plant and the animal inmates. One tank established 

 in 1909 was exhibited. The water has never been changed, nor 

 has any form of plant or animal living or dead, been added or 

 removed during the four years. A slight drawback to this type of 

 aquarium is the difficulty of keeping large fishes, for in a balanced 

 tank the plant life should be about one hundred times greater in 

 bulk than the animal life; yet on the other hand, once such an 

 aquarium becomes settled it remains perfectly clear, and swarming 

 with ever-changing forms of life, for an indefinite period. No 

 attention is required other than the occasional addition of water to 

 make good the loss from evaporation during dry weather. As a 

 rule, plants possessing stomata, and such vegetable-eating organ- 



