QUESTIONS 137 



QUESTIONS. 



1. What do we mean by the term pure culture? 



2. What is a culture medium? 



3. What is a natural, what an artificial culture medium? 



4. What are the requirements of a culture medium on which bacteria can be 

 grown? What should be the reaction of a culture medium? 



5. What substances are used to prepare solid transparent culture media? 



6. At what temperatures do the ordinary gelatin and agar culture media melt ? 



7. Describe the method of obtaining sterile blood serum from a horse. 



8. How are the artificial culture media generally sterilized ? 



9. What is meant by the term sterilization ? 



10. What is an Arnold steam sterilizer? 



11. What is an autoclave? 



12. What is meant by continuous sterilization? 



13. What is TyndalPs fractional sterilization method? What is its underlying 

 principle ? 



14. How is agar, how is gelatin sterilized, and why? 



15. How is blood serum in tubes sterilized and why? 



16. How is the blood for use as a bacterial culture medium generally obtained 

 and how treated afterward? 



17. How is the glassware used for work in bacteriology sterilized? 



18. How should new glassware be treated before use in work with bacteria and 

 why? 



19. Give the formula for the preparation of the ordinary nutrient bouillon. 



20. What is meant by a +1.5 bouillon? How does it act toward the phenol- 

 phthalein, how toward the litmus indicator? 



21. What is the meaning of the word indicator as used in chemistry? 



22. What is the meaning of the word normal, or standard, or molecular solution 

 in chemistry? 



23. How is a T ^ (one-tenth) normal solution of NaHO (caustic soda) prepared? 



24. Give the formula for preparing the ordinary gelatin as used in the bac- 

 teriologic laboratory. 



25. Give the same formula for agar. 



26. How is agar filtered or cleared? 



27. Name some substances frequently added to the ordinary culture media. 

 Why added? 



28. What is a glucose gelatin, what a lactose litmus gelatin, what a glycerin 

 agar, what a litmus milk? 



29. How is Loeffler's blood serum mixture prepared? 



N. B. The student should only attempt to commit to memory the formulae 

 for the most commonly used artificial culture media, such as ordinary gelatin 

 and agar and those indicated in questions 28 and 29. It is unnecessary to commit 

 to memory all of the formulas given above. 



