90 MICROBES, 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 algze termed Phy- 
cochromycee, 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, 
