CHAPTER II 



THE FORM AND STRUCTURE OF BACTERIA 



THE bacteria that may be observed under the micro- 

 scope in a drop of stagnant water, or of decomposing 

 beef-broth, may be grouped under three main types 

 as regards form. They are, the spherical, the cylindrical, 

 and the spiral forms. These types have been conveniently 

 described as resembling billiard balls, lead pencils, and 

 cork-screws. The organisms occur singly or in aggre- 

 gations of two or more. 



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Fig. 4. Spherical bacteria, 1. Planosarcina ureoe; X 2,580. (Beyerinck.) 

 2. Streptococcus. (Weigmann.) 3. Coccus lactis viscosi. (Gruber.) 4. 

 Sarcina aurantiaca. (Pammel.) 5. Micrococcus Sornthalii; X900. (Adametz.) 



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