68 INFECTION, PHAGOCYTOSIS, OPSONINS 



QUESTIONS. 



1. What is an infectious disease? 



2. What is a contagious disease ? 



3. Name some infectious diseases, also some contagious diseases. 



4. How do microorganisms produce disease? 



5. What is a toxin, a soluble toxin, and an intracellular or endotoxin? 



6. Name some pathogenic bacteria which form soluble toxins. How can 

 they be obtained free from bacteria ? 



7. Name some bacteria which form only insoluble endotoxins. How are 

 the latter set free ? 



8. Name a pathogenic bacterium which multiplies very freely in the body 

 and one which multiplies sparingly, but produces a powerful soluble toxin. 



9. What is meant by a virulent bacterium and by virulency? 



10. What is meant by individual susceptibility? 



1 1 . What is meant by attenuation ? 



12. What methods can be employed to attenuate virulent bacteria? 



13. What is meant by an a virulent bacterium? 



14. What is a mixed infection ? 



15. What is symbiosis? 



16. Why does not an infectious disease attack every individual? Why does it 

 not always kill? 



17. What is a phagocyte? What is phagocytosis? 



18. Who first studied phagocytosis, and in what animals? 



19. What happens if we inject washed goose-blood corpuscles into the peri- 

 toneal cavity of a guinea-pig? 



20. What is the procedure of washing mammalian or avian blood corpuscles? 



21. What kind of cells of higher animals possess the power of phagocytosis? 



22. What are macrophages? What are microphages ? How do they differ as 

 to their phagocytic properties? 



23. How can the phagocytosis of anthrax bacilli be demonstrated? 



24. How do very virulent streptococci act with reference to phagocytosis? 



25. What is meant by immunity? 



26. What is an attenuated virus or vaccine? 



27. What are the three stages of phagocytosis? 



28. What is positive, negative, and indifferent chemotaxis? 



29. What is an opsonin? 



30. What is the effect of washed leukocytes upon a bacterial emulsion? What 

 is their effect in the presence of blood serum ? Why is this effect produced ? 



31. Describe comparative experiments to show the effect of the absence or 

 presence of serum upon phagocytosis. 



32. Describe such a set of experiments with dog's leukocytes and anthrax 

 bacilli. 



33. Are opsonins present in normal healthy animals in very variable or in 

 rather constant amounts? 



34. How can the amount of opsonin present be estimated? 



35. What about the amount of opsonin in chronic bacterial infections? 



36. What is meant by the opsonic index? How is it estimated? 



37. If in the mixture of healthy sera in one experiment 2001 eukocytes have 

 taken up 250 bacteria, and in the experiment with the serum of the sick person 

 or animal only 100 bacteria have been taken up by phagocytosis, what is the 

 opsonic index of the latter serum? 



38. What is the effect of vaccine or bacterine injection upon the opsonic 

 index ? 



39. What is the negative phase after vaccine injection? What is the positive 

 phase ? How long does the latter generally last ? What occurs then ? 



40. Describe in detail how to obtain the opsonic index in case of a chronic 

 staphylococcus infection in a horse 



