27. What is meant by the Rubber Belt around the world?
28. What countries are the principal producers of rubber?
29. Why is the worker on a plantation better off than one who lives in the jungle?
30. When are trees ready to be tapped?
31. How are trees tapped?
32. How is rubber "cured" in the jungle?
33. How is it "cured" on the plantation?
34. Why is rubber manufacturing peculiarly an American industry?