370 GENERAL SCIENCE 



It cannot be applied directly to plants, but the emulsion 

 mentioned above may be used against all sucking insects 

 and scale when diluted to 20 gallons. 



In some places the San Jose scale on orange trees is 

 treated by inclosing the tree in a tent and applying 

 hydrocyanic acid gas. This gas is very poisonous and 

 care should be taken that none of it is breathed. 



Weevils in grains may be killed by carbon disulphide 

 placed in a dish and set on the surface of the grain. It 

 is very volatile, the heavy vapor settling slowly through 

 the entire bin, killing the insects as it goes. Care should 

 be taken that no flames are brought near carbon disul- 

 phide, as its vapor is very combustible. 



QUESTIONS 



1. How do one-celled plants and one-celled animals differ? 



2. What is the lowest form of animal life that has a nervous 

 system ? 



3. Why does an earthworm die when placed in the sun? 



4. How may we most easily destroy the house fly? 



5. How do reptiles differ from fishes? From amphibians? 



6. How do birds differ from reptiles? 



7. Name five carnivorous mammals. Ten herbivorous mam- 

 mals. Three omnivorous mammals. 



8. What class of mammals does man use for food ? 



9. What amphibians are used as food by man? What mol- 

 lusks? What is the lowest class of animals used as food? 



10. Name five food products besides flesh that are furnished by 

 animals. 



11. Is the cat a useful or injurious animal? 



12. Name five animals that are useful to man and are not used 

 as food by him. How is each animal useful? 



13. Are there birds that are classed as pests? 



14. What is the source of neat's foot oil? Glue? Gelatine? 

 Tallow? Ivory? 



15. What uses are made of animal hair? 



