CHAPTER III 



THE BACTERIA IN GENERAL 



CLASS II. SCHIZpMYCETES 



The name Schizomycetes comes from two Greek roots (ax'i-^oi, 

 I split + ijLVKr]s, a fungus) which combined are equivalent to the term 

 splitting fungi, or fission fungi in allusion to the manner in which the 

 bacterial cells divide. The Germans call them Spaltpilze, which is 

 the German way of expressing the same thing. The name bacteria 

 is in American science used in a general sense to include all of the 

 Schizomycetes without reference in particular to the genus Bacterium. 

 In popular use, such as newspaper articles, these lowly plants are 

 described as germs, microbes, or microorganisms. These English 

 synonyms are, however, inexact, having different shades of meaning 

 and are used in different ways in common speech, as consultation with 

 any large dictionary of our language will show. There is no ambiguity, 

 if we speak of all the Schizomycetes as bacteria, or bacterial organisms. 

 These plants are generally unicellular, or the single cells are united 

 into a coenobium. These coenobia are filamentous, sheet-Uke, or in 

 groups, seldom arranged in fructification-like masses of definite form, 

 as is the case with the Myxobaderia. All cells of the coenobium are 

 alike and only in the highest developed forms do we find a differentiation 

 into basal cells and filament cells. The heterocyst, found in the blue- 

 green algae, is totally absent. The cells of bacteria are the smallest 

 of plant cells; for example: Micrococcus progrediens has a diameter 

 of o.i5ju and Spirillum parvum has a thickness of o.i to 0.3^1, but yet 

 smaller are the ultramicroscopic organisms, which have come into 

 prominence recently as the cause of certain diseases. The smallest 

 bacteria stand at the borderline o,f what is with the best lenses and 

 optimum illumination the practical limit of microscopic vision. On 

 the other hand, with the application of the ultraviolet light of short 

 wave length in microphotography, it has been possible to obtain an 

 image of small objects whose enlargement has been 4000-fold. It 

 has been possible with the ultramicroscope of Siedentopf and Zsig- 



