64 PRACTICAL BOTANY. 



The nutrition of the Bacteria is in general that of sap- 

 rophytic plants, i.e., of those that live on decomposing 

 organic matter. Some forms live as parasites. This is 

 the fact in the case of the forms which thrive in the liv- 

 ing tissues of animals, producing disease. At least three 

 species Bacillus virens, Bacterium chlorinum, and Bacte- 

 rium viride are known to contain chlorophyl, and their 

 nutrition must be in part or wholly holophytic, i.e., like that 

 of the green plants. Bacillus amylobacter also produces 

 a substance which, when treated with a solution of iodine, 

 gives a blue color which is characteristic of the reaction 

 of starch. Starch is the product of chlorophyl-beariiig 

 plants. Some species live and multiply in solutions that 

 contain no organic matter, a fact which tends to support 

 the theory of evolutionists that the earliest forms of life 

 were Protista, and that plants and animals have developed 

 from these by gradual evolution in different directions, 

 which have been determined by local conditions. 



Many forms of Bacteria possess the power of moving 

 from place to place. These motions are in some cases 

 believed to be produced by the action of cilia ; in other 

 cases it is believed that they are caused by contractile 

 movements of the protoplasm. 



The ordinary mode of multiplication of Bacteria is by 

 the transverse fission, of the cell. In some cases the 

 newly formed cells separate ; in other cases they remain 

 in contact, held together by a hyaline, gelatinous secre- 

 tion, forming filaments of some length. Another mode of 

 continuing the existence of the organisms, which obtains 

 in some species when the conditions of nutriment and 

 moisture are unfavorable for the fission of the cells, is 

 by the formation of resting spores. These spores form in 

 the center of most of the cells, one in each. They are 

 the resting condition of the organism and possess much 

 greater vitality than the cells. In the spore condition 



