CLASSIFICATION OF THE BACTERIA 21 



well understood, but in some cases it is apparent that the 

 reserve carbohydrate food material resembles glycogen, in 

 others it is perhaps more closely related to starch. Gran- 

 ules which give the starch color reaction with iodine have 

 been termed granulose. Certain bacteria which live in 

 water containing hydrogen sulphide show sulphur granules 

 in the protoplasm. It is possible that in some cases oil drops 

 may be detected. 



Flagella. — A very few species of cocci, many species of 

 bacilli, practically all species of spirilla, and none of the 

 filamentous bacteria, possess organs of locomotion termed 

 flagella. These are exceedingly slender, so slender in fact 

 that they are observed under the microscope usually only 

 by the most careful staining methods. They may be re- 



Fig. 5. — Flagella of bacteria. A. Non-flagellate or atriehoua bac- 

 teria. B. Bacteria with single polar flagellum, monotrichous. 

 C. Bacteria with clusters of polar flagella, lopotrichous. D. Bac- 

 teria with flagella on all sides, peritrichous. 



garded as differentiated protoplasmic organs projecting 

 through the cell wall to the outside. They are relatively 

 long, sometimes many times the length of fhe cell which 

 produces them. By means of a spiral or corkscrew motion 

 these flagella propel the organism. 



Those species of bacteria which do not possess flagella are 

 said to be atrichous. Some species possess a single flagellum 

 at one end of the cell. Such organisms are termed mono- 

 trichous. Organisms having a tuft of flagella at one end 

 are termed lophotrichous. Those bacteria which have fla- 

 gella distributed over the entire surface of the cell are said 



