THE CONSERVATION OF OUR NATURAL RESOURCES 471 



coal and iron ; others are petroleum, natural gas, lead, zinc, gold, 

 silver, and stone. The methods of mining these minerals, and 

 of using them after they are mined, are extremely wasteful. 



Throughout this book an attempt has been made to indicate 

 the value of animals as a natural resource. The bisons have been 

 practically exterminated ; millions of passenger pigeons have 

 been destroyed until not a single one remains alive to-day; the 

 elk, pronghorn antelopes, mountain sheep, and other big game 

 animals which were formerly abundant have decreased so 

 greatly that now very few exist outside of zoological parks ; the 

 alligators, the seals, and the whales have been killed without 

 regard to the future; our game birds and insectivorous birds 

 have been persecuted and hordes of insects thus let loose upon 

 our fields and orchards ; the terns, humming birds, and egrets 

 are destroyed for their plumes ; our waters are rapidly being 

 depleted of fish, oysters, lobsters, etc. ; and finally even human 

 lives are sacrificed because of the neglect of opportunities to 

 promote health by preventing the dissemination of disease germs. 



Practical zoology is concerned with the conservation of our 

 natural resources so far as they are influenced by animals. What 

 can be done to prevent the waste of human lives has been in- 

 dicated in the crusades against the house (typhoid) fly and the 

 yellow fever mosquito. Some of the efforts of the national, 

 state, and city governments to prevent the destruction of useful 

 animals have likewise been described in connection with the 

 song birds, fish, and game. Attempts to stem the tide of de- 

 struction have been made and are now in progress, as indicated 

 by the review of the work being done by some of our scientific 

 institutions, as presented in Chapters XLI and XLIII. This 

 review indicates what our thoroughly enlightened people are 

 trying to do for the conservation of some of our natural resources. 



REFERENCES 



The Conservation of Natural Resources in the United States, by C. R. Van 



Hise. The Macmillan Co., N. Y. City. 

 Our Wasteful Nation, by R. Cronau. Mitchell Kennerley, N. Y. City. 



