False colour transmission electron micrograph (shadow technique) of the bacterium Escherichia coli, a normal inhabitant of the human intestine. Under certain conditions it may become harmful & cause infection in the intestinal or urinogenital tracts. The hairlike appendages around the bacterium (shown by shadowing), are pili, structures associated with bacterial conjugation. This specimen is in the early stages of binary fission, the process by which the bacterium divides in two. E. coli is the organism most commonly used in genetic engineering experiments. Magnification: x14,700 at 35mm size, x29,400 at 6x7cm size.