DIVISION I. 

 SCHIZOMYCETIC FEEMENTATION. 



SECTION I. 



GENERAL MORPHOLOGY AND PHYSIOLOGY OF 

 THE SCHIZOMYCETES. 



CHAPTER I. 

 FORM AND DIMENSIONS. 



27. Forms of Growth. 



THE cell forms of all the Scliizomycetes may be typified by a small 

 rod ; hence these organisms are generally known by the name of 

 bacteria, from the Greek rendering of this descriptive term, lak- 

 terion, a rod. 



When the dimensions of a bacterial cell are equal in all 

 directions, it is termed a coccus or micrococcus, monas or cocco- 

 bacterium. On the other hand, when the cell is not iso-diametrical, 

 but exhibits a difference between length and breadth, the name 

 bacillus, or elongated rod, is applied, provided the length is at 

 least double the breadth ; but when the former does not attain 

 this relative size, we then speak of bacteria. This latter term 

 has therefore a twofold application : a general one, in so far as all 

 the fission fungi are briefly called " bacteria ; " and a special one, 

 referring only to a particular form of growth, as just mentioned. 



A bacterial cell of the bacillus type which, during a certain 

 physiological process (to be studied later on under the name of 

 " spore formation "), swells out like a spindle or club, is generally 

 termed a clostridium. 



If the rod is arched like a bow or bent in the form of a 

 comma, it is spoken of as a vibrio, and if the bends be repeated 

 several times, then a wavy kind of growth denoted spirochsete 

 ensues. When the bend departs from the level plane and shapes 

 itself in such a manner that it can be applied to the surface of a 

 cone or cylinder, the type of growth becomes spiral, and is 

 designated spirillum. An illustration of these forms is given in 



