This video shows a neutrophil (a type of white blood cell) chasing a staphylococcus aureus bacterium. The video was recorded by biochemistry professor David Rogers of Vanderbilt University in the 1950s. Notes on the movement by med school professor Thomas P. Stossel:
Contraction waves are visible along the surface of the moving cell as it moves forward in a gliding fashion. As the neutrophil relentlessly pursues the microbe it ignores the red cells and platelets. However, its leading edge is sufficiently stiff (elastic) to deform and displace the red cells it bumps into. The internal contents of the neutrophil also move, and granule motion is particularly dynamic near the leading edge. These granules only approach the cell surface membrane when the cell changes direction and redistributes its peripheral "gel." After the neutrophil has engulfed the bacterium, note that the cell's movements become somewhat more jerky, and that it begins to extend more spherical surface projections.
http://www.biochemweb.org/neutrophil.shtml via Geekologie