14 / A MANUAL OF BACTERIOLOGY 

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Always the non-flagellated end of the dividing cell which 

 bears the flagella of the new cell. Under favourable 

 conditions reproduction may be very rapid, fission occur- 

 ring every twenty or thirty minutes (Klein), so that, the 

 increase being in a geometrical ratio, the number of 

 individuals which might arise from a single bacterium 

 in three or four days is almost inconceivable, and would 

 en masse weigh thousands of tons ; fortunately there 

 are many checks to such a rapid multiplication. Fre- 

 quently, although the protoplasm divides, the division 

 of the cell-membrane is incomplete, resulting in a loose 

 union of the cells with the formation of a pseudo-filament. 

 These filaments often become much curved and twisted, 

 forming tangled masses, owing to fission taking place 

 in the cells in the middle of the filament as well as at the 

 ends, so that the filaments have to become curved to 

 make room for the new cells. 



Reproduction by spore formation is met with in some 

 species, and is generally described as being of two varieties. 

 In one, endogenous or endospore formation, a refractile 

 round or ovoid body forms within the bacterial cell, 

 the development of which can be watched under the 

 microscope. Rowland described the process of spore 

 formation as follows : Refractile, oily-looking droplets, 

 which do not stain with roseine, appear and ultimately 

 coalesce, forming the spore. The cell-plasma at the same 

 time diminishes and retracts from the cell-membrane. 

 The roseine-staining granules increase in number and 

 aggregate into two spherical masses, which dispose them- 

 selves one at each end of the cell. The cell-membrane 

 collapses somewhat, and, when the spore is fully formed, 

 ruptures transversely, leaving two cup-shaped receptacles, 

 in which the granules and remains of the plasma are still 

 recognisable. Only one spore develops in each cell, and 

 the spores serve to perpetuate the race when it is 



