QUESTIONS 25 



animals. It derives its nutrition from the contents of the large intes- 

 tine, and is harmless except when it invades such organs as the gall- 

 bladder, the urinary bladder, etc. 



Symbiotes. There are some parasitic microorganisms which are not 

 only harmless but which are beneficial or even absolutely necessary. 

 For instance, there are bacteria living on the roots of higher plants 

 (clover) without which these plants could not obtain their nitrogen 

 supply. Certain bacteria occur in the human and animal vagina 

 which keep the secretion of the organ acid and tend to prevent dis- 

 ease-producing microorganisms from gaining entrance into the uterus. 

 Such necessary or beneficial parasites are called symbiotes. The term 

 symbiosis is, however, also used in bacteriology in a very different 

 sense namely, for two bacteria living together and producing by 

 their united efforts a more virulent form of disease. 



QUESTIONS. 



1. What are the distinguishing characters between an animate and an inan- 

 imate object of nature? 



2. What is an organ? What an organism? 



3. What is a unicellular organism? 



4. What is a microorganism or microbe ? 



5. What is a pathogenic microorganism? 



6. What is an infectious disease? 



7. Name some diseases which occur only in man and not in the domestic 

 animals ? 



8. Name some diseases which occur in domestic animals and not in man. 



9. Name some diseases common to man and to domestic animals. 



10. Name a harmless non-pathogenic microorganism which looks very much 

 like the anthrax bacillus. 



11. What is the role of the microorganisms in general in nature ? Why are 

 they essential for the maintenance of life on our planet? 



12. What is the meaning of the term saprophyte? 



13. What is the meaning of the term parasite? 



14. What does the term ubiquitous mean? 



15. What is an obligate parasite? Name such a microorganism. 



16. Is the anthrax bacillus an obligate parasite or not? 



17. What is a facultative, what an obligate saprophyte? 



18. "V^hat is an ectogenous parasite? 



19. What is an entogenous parasite? 



20. What is a commensale? 



21. Name a bacillus which lives in the intestines of man and domestic animals 

 as a commensale. 



22. What are symbiotes? 



23. What does the term symbiosis, when used in connection with pathogenic 

 bacteria, generally signify ? 



