52 Microbes and You 



its own power? We can answer that inquiry by stating that loco- 

 motion, in itself, is a poor criterion for judging whether a living 

 thing should be classified as a plant or as an animal. There are 

 other more important differences which have been accepted by 

 persons who devote their lives to this field of study we call 

 Taxonomij— the science of classification. 



While bacteria do not exhibit all of the characteristics generally 

 ascribed to plants, they do have more plant features than animal 

 characteristics. The presence of a firm, thick, demonstrable cell 

 wall, the ability to combine simple substances for their own use 

 ( CHEMOSYNTHESis ) , and the capacity to utilize only relatively 

 simple compounds taken in solution (holophytic nutrition), 

 are strong arguments favoring the classification of bacteria as 

 plants. The dividing line between the plant and the animal 

 kingdoms might be said to pass through the bacteria. 



CLASSIFICATION OF BACTERIA 



It has been convenient for scientists to place living things into 

 various groups, or classifications, in order to point out their relation 

 to other living; thino;s, and to demonstrate how much more 

 specialized some organisms are than others. The "big words" 

 emploved by scientists are often frightening to the novice, but 

 don't think for one moment that these same words are not also 

 disturbing to workers who have been engaged in the field for a 

 good many years. Not all bacteriologists agree with the names 

 given to microorganisms by taxonomists. The very fact that 

 taxonomy is not static, that changes are continually being suggested 

 and adopted by those individuals most concerned, indicates that 

 even the leaders in the field cannot always agree. Compromises 

 must be made if we are to have any kind of a workable system 

 for classifying microbes. This agreement becomes important not 

 only for American biologists, but for scientists engaged in labora- 

 tories throughout the world. An International Microbiological 

 Congress meets every few years in an attempt to thrash out knotty 

 biological problems, and the questions relative to taxonomy have a 

 habit of finding their way near the top of the agenda. Without 



