14 PRACTICAL DAIRY BACTERIOLOGY 



SPIRAL BACTERIA. (Fig. 3, a.) Spirillum 



The genus BACILLUS is further divided as follows: 

 Bacilli with only one flagellum (Fig. 4, C) 



are named Monotrichic Bacilli, or Pseudomonas 



Bacilli with a tuft of flagella at one end 



(Fig. 4, B) are called Lophotrichic Bacilli 



Bacilli with flagella over the ivhole body 



(Fig. 4, A) are called Peritrichic Bacilli 



It will thus be seen that the term Bacteria applies to the 

 whole group of organisms that multiply by divis- 

 ion, whose study constitutes the study of Bac- 

 teriology, while the term Bacterium refers to a 

 single division of the group, viz : the non-motile, 

 rod forms. The term Bacillus should apply to 

 motile forms only. The names Bacillus and Bac- 

 SARCINATYPE ter ^ um are sometimes confused; for example, the 

 tubercle Bacillus is really a Bacterium since it is 

 non-motile, but the name Bacillus was given it years ago before 

 the above distinctions were recognized, and it has not been 

 changed. Some other bacteria named twenty years ago retain 

 their earlier names in some books, but they are slowly having 

 their names brought into harmony with the above distinctions. 

 The term Coccus is applied to any spherical organism of the 

 group bacteria. 



PLANTS OR ANIMALS 



The question whether bacteria are plants or animals has 

 been much discussed and answered in both ways. The reason 

 for the uncertainty is the fact that our biologists are unable to 

 give any clear distinction separating animals from plants, and 

 with any definition that they can give, bacteria show relations 

 to both plants and animals. The method of forming spores 

 allies^them to plants, while their frequent motility, together with 

 the fact that they live upon foods similar to animals, allies 



