43 



J. Beggiatoaceae. 



Only one genus known {Beggiatoa Trev. ) which is scarcely separ- 

 able from Oscillaria. Character as given under the family. 



Of the genera the Streptococcus, Micrococcus, Bacterium, 

 Bacilhis, Microspira and Spirillum contain the most import- 

 ant of the pathogenic bacteria. The familiar genus Staphy- 

 lococcus of an older classification is included in the genus 

 Micrococcus by Migula. It is important that the distin- 

 guishing characters of these genera are thoroughly learned. 



§63. General directions. Read the references* on the 

 morphology and classification of bacteria. 



lycarn from the text-books and lecture notes the more 

 essential elements in the structure of bacteria. 



Inoculate a tube of bouillon from a culture which will be 

 furnished of each of the following bacteria and place the 

 inoculated tubes in the incubator. 



(i) A streptococcus (Streptococcus ) 



(2) A micrococcus (Micrococcus ) 



(3) A staphylococcus (Staphylococcus ) 



(4) A sarcina (Sarcina lutea ) 



(5) A non-motile rod-shaped organism. (Bacterium ) 



(6) A motile, rod-shaped organism (Bacillus ) 



(7) A spiral, rod-shaped organism ( ) 



EXERCISE XV. 



IDENTIFYING GENERA AMONG BACTERIA. 



§64. General directions. Carefully describe each of the 

 bouillon cultures made in Exercise XIV. 



Prepare and examine a hanging drop preparation from 

 €ach of the cultures, and de,scribe the appearance (form) of 



*Migula, Die Naturlichen Pflanzenfamilien, Lieferung 129, teipzic, 1896. 

 Migula, System der Bakterien, 1897. Fischer, Jahrbiicher tUr wissenschaft- 

 liche Botanik, Band XXVII, Erstes Heft. 



