REPRODUCTION OF BACTERIA 45 



they can be assimilated they must be digested and broken 

 up into somewhat simpler compounds. The food used by 

 most bacteria requires little or no chemical alteration before 

 it can be assimilated by the protoplasm of the cell. Bacteria 

 are not compelled to search about for food as some animals 

 do, but live naturally only in the midst of nutrient material. 

 It should be noted that reproduction in some protozoa (amceba) 

 takes place for a time as rapidly as in the bacteria, but only 

 after the cell has received and assimilated sufficient food. 

 On account of their natural conditions of life bacteria can 

 grow faster and reproduce more rapidly than any other animal 

 or plant cell. There is a great variation among bacteria in 

 regard to the rapidity with which they reproduce. Some 

 species are exceedingly rapid (B. subtilis), and others are 

 comparatively slow (Bact. tuberculosis). 



The flagella of the motile bacteria do not in any way 

 interfere with the process of fission among these species. 

 In the lophotrichous bacteria the non-flagellate end of the 

 dividing cell furnishes flagella for one of the new individuals. 

 The other cell uses the old flagellum of the parent. 

 These old flagella may be carried for generations. The con- 

 tiguous ends of the cells never produce any flagella. In amphi- 

 trichous bacteria new flagella are provided by both new indi- 

 viduals. These cells therefore have a new and an old set of 

 locomotive organs. It is held by some that amphitrichous bac- 

 teria do not exist, and that the bipolar flagella result during the 

 process of fission of a monotrichous bacterium, the new individ- 



