Continuously variable amplitude contrast microscopy for the detection and study of microorganisms in soil.

A new type of phase microscope was used to detect and observe the microflora in soil and to differentiate cells and spores from soil debris. This microscope provides a continuous variation in the amplitude ratios between undeviated and deviated beams of light, and the microbial cells, spores, and debris in soil change in appearance to a differing degree in response to the changes in amplitude ratio.