43 



5- 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, 

 Bacillus, 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. 



lyearn 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. 



(1) 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 

 each of the cultures, and describe the appearance (form) of 



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

 Migula, System der Bakterien, 1897. Fischer, Jahrbucher fur wissenschaft- 

 liche Botanik, Band XXVII, Erstes Heft. 



