40 THE FUNDAMENTAL PRINCIPLES. 



enzymes which they secrete. Some cause a reduction of the 

 nitrites. 



12. Others oxidize nitrogen into nitrites, and even nitrates. 



13. Finally, some bacteria cause disease in man and animals. 

 These, called pathogenic, are of the greatest interest to 

 physicians, and it is the discovery of this pathogenic prop- 

 erty which in the last twenty years has given such an 

 impetus to the study of bacteriology. 



QUESTIONS. 



Who first discovered microorganisms iu decaying vegetable infusions ? 



To what kingdom were they thought to belong at first? 



What classification is generally accepted at present ? 



Name the three varieties of fungi. What criticism may be made of this 

 classification ? 



Give a proper definition of bacteria. 



Of what does the bacteria cell consist ? 



What causes some bacteria to have a capsule ? Are the capsules generally 

 retained by bacteria when grown artificially ? 



What causes some bacteria to be more difficult of staining than" others? 



Into what three varieties or species are bacteria divided ? 



What are megacocci ? Micrococci ? Diplococci ? Merismopedia ? Sarcinsc ? 

 Streptococci ? Staphylococci ? Ascococci ? 



What is the shape of bacilli ? When are they said to be slender? When 

 thick ? How do they develop ? What are spirilla ? Can one species develop 

 into another species? 



What are the limits of size of bacteria ? 



What is a mikron ? 



What is the average length of the pathogenic bacteria? 



How do bacteria multiply? Describe this process in the case of cocci, 

 bacilli, and spirilla? 



What are spores, and how are they formed ? 



How do spores compare with bacteria in their power of resisting injurious 

 external influences and of staining ? To what is this due? 



What is meant by a clostridium ? 



What is meant by a drummer-bacillus ? 



What is the name of the ordinary spores? 



What is meant by arthrospores ? 



What is the theory of spore-formation ? 



What is meant by motility, and what species have this power? 



What are flagella? 



What names are given to bacteria according to the position and number 

 of their flagella? 



What is meant by aerobic bacteria? Anaerobic? Facultative aerobic? 

 Facultative anaerobic? 



What are saprophytes? Parasites? 



What conditions are required for the proper development of bacteria? 



What is the most favorable temperature for bacterial growth ? 



What is the effect of cold? Of excessive heat? 



How do spores differ from bacteria in their reaction to heat and cold ? 



