THE CLASSIFICATION OF BACTERIA 55 



b. Cells with organs of motion (flagella). 



(1) Cells with i, very rarely 2-3, polar 



flagella 2. Microspira 



(2) Cells with polar flagella, in tufts 



of from 5 to 20 3. Spirillum 



Cells flexuous 4- Spirochata 



4. GENERA BELONGING TO THE FAMILY CHLAMYDO- 

 BACTERIACE^: 



I. Cell contents without granules of sulphur. 



a. Cell threads unbranched. 



1 i) Cell division always only in i plane i . Streptothrix 



(2) Cell division in 3 planes previous 



to the formation of conidia. 



(a) Cells surrounded by a very 



delicate, scarcely visible 



sheath (marine) . . . .2. Phragmidiothrix 



(b) Sheath clearly visible (in 



fresh water) 3. Crenothrix 



b. Cell threads branched (pseudo- 



branches) 4- Cladothrix 



II. Cell contents containing sulphur gran- 

 ules 5- Thiothrix 



5. GENERA BELONGING TO THE FAMILY BEGGIATOACE^E 



Only one genus known (Beggiatoa Trev.), which is scarcely 

 separable from Oscillaria. Character as given under the family. 



Of these genera Streptococcus, Micrococcus, Bacterium, 

 Bacillus, Microspira, and Spirillum contain the most important 

 of the pathogenic bacteria. The familiar genus Staphylococcus 

 of older classifications is included in the genus Micrococcus by 

 Migula. It is important that the distinguishing characters of 

 these genera be thoroughly learned. 



REFERENCES. Migula, Die natiirlichen Pflanzenfamilien, Liefe- 

 rung 129, Leipsic, 1896. Migula, System der Bakterien, 1897. 

 Fischer, Jahrbiicher fiir wissenschaftliche Botanik, Band XXVII, 

 Erstes Heft. 



