90 MICKOBES, FERMENTS, AND MOULDS. 



is dried up, the protoplasm contracts and forms spores, 

 which, when set at liberty by the rupture of the cell- 

 wall, germinate and give birth to fresh bacteria. The 

 only difference consists in the fact that ferments may 

 produce several spores in each cell, while bacteria 

 never produce more than one. 



Bacteria were, as we have already said, for a long 

 while classed with fungi under the name Schizomycetes. 

 But recent researches into their organization, and more 

 especially into their mode of reproduction, show that 

 they resemble a group of inferior algae termed Phy- 

 cocliromyceoe, which includes Oscillaria, Nostocs, and 

 Chroococcus, species generally furnished with chloro- 

 phyl. Bacteria represent a similar group devoid of 

 chlorophyl. Zopf, in a treatise recently published, goes 

 still further : he asserts that the same species of alga 

 may at one time be presented in the form of a plant 

 living freely in water or damp ground by means of 

 chlorophyllaceous protoplasm, and at another in the 

 form of a bacterium or parasitic microbe, devoid of 

 chlorophyl, and nourished at the expense of organic 

 substances which have been previously elaborated by 

 animals or plants, thus accommodating itself, accord- 

 ing to circumstances, to two very different modes of 

 existence. 



