GENERAL BIOLOGY. 



19 



matter. That such fluids readily putrefy is owing to the pres- 

 ence of bacteria, the vital action of which suffices to break asun- 



Fis. 30. 



Fig. 31 



Fia. 33. 



Fig. 39.— Micrococcns, very like a spore, but nenally much smaller. 



Flo. 30.— Bacterium. 



Fis. 31.- Bacillus. The central filament presented this segmented appearance as the 

 result of a process of transverse division occurring during ten minutes^ obser- 

 vation. 



Fig. 32.— Spirillum; various forms. The first two represent vibrio, which is possibly 

 only a stage of spirillum. * 



Fig. 33. — A drop of the surface scum, shovring a spirillnm aggregate in the resting 

 state. 



der complex chemical compounds and produce new ones. Some 

 of the bacteria require oxygen, as Bacillus anthrads, while 

 others do not, as the organism of putrefaction. Bacterium 

 termo. 



Bacteria are not so sensitive to slight variations in tempera- 

 ture as most other organisms. They can, many of them, with- 

 stand freezing and high temperatures. All bacteria and all 

 germs of bacteria are killed by boiling water, though the spores 



