358 Co7istmit Care Is Needed for Health unit vi 



6. You now know that (a) malaria is caused by a protozoan carried 

 by mosquitoes, and (h) mosquitoes breed in swamps. Outline the ex- 

 periments that must have been performed to prove that malaria can be 

 acquired only by the bite of a mosquito and not by "bad air." 



7. Study the diagram, Figure 310. It shows a mosquito injecting a 

 parasite into the human blood. How did this mosquito get parasites into 

 its body in the first place? Under what conditions would it not have in- 

 jected parasites? We speak of the mosquito as the carrier. If the mosquito 

 could tell the story how would the story differ? 



8. The mosquito's life is short. How does the protozoan profit by 

 spending part of its life in man? How does the protozoan profit by using 

 the mosquito as the second host? 



9. Draw an outline diagram of the human body, indicating the chief 

 organs. By the use of arrows, show on your drawing the parts through 

 which the hookworm parasite passes. 



10. List in a column the following common practices of a health de- 

 partment: isolation, control of water supply, sewage disposal, pasteuri- 

 zation of milk, food protection, food inspection, control of carriers, res- 

 taurant inspection, mosquito extermination, rat extermination, public 

 education. Next to each, write the name of the disease (from the list 

 given below) which should be controlled by this method. Remember 

 that some diseases must be controlled in several ways. Bubonic plague, 

 typhoid fever, diphtheria, malaria, cholera, tuberculosis, yellow fever, 

 hookworm disease, smallpox, septic sore throat, trichinosis. 



Further Activities in Biology 



1. Visit a large food market. Report on the precautions that are taken 

 in the handling of food. Can you suggest any practicable improvements? 



2. Visit a large milk distributing plant in your city. Note particularly 

 the steps taken to prevent contamination of the milk. If you live in the 

 country, visit a farm that supplies milk to your neighborhood. What 

 precautions do they take to keep the milk pure? 



3. Are you sure that the water supph^ in your home is pure? What 

 are the possible sources of contamination? Investigate and report. 



4. How is sewage disposed of in your community? Is it likely to con- 

 taminate the water supply? The bathing beaches? 



5. Capture a housefly and let it walk across a sterile agar plate. Put 

 the plate away in a warm place for a few days. What do you discover? 



6. You will find Surgeon General Gorgas' account of his work in Cuba 

 interesting reading. And if you can get a copy of the Scientific Monthly 

 for the year 191 5 published by the American Association for the Ad- 

 vancement of Science, read The Inside History of a Great Medical Dis- 

 covery by A. Agramonte. Read also Defoe's The History of the Plague. 

 Prepare a report to be read in class on Zinsser's Rats, Lice and History. 



