A new series for 1999
video clips taken by Edward Cowen, UK
(Compiled for the Web by Dave Walker)
Video in 'avi' format included.
Click here for animated gif version
if your computer doesn't support 'avi'.
In the third of this Video Gallery series we show two video clips taken by Edward Cowen, UK. The video clips show two fascinating aspects of protozoa. One shows the movement of cilia and the other shows the extending pseudopod of a species like Amoeba. One uses darkfield illumination and the other phase contrast. Both forms of illumination can be very effective for showing detail in such organisms.
The second sequence uses Edward's home adapted phase contrast outfit. This setup was also used to video the Spirochaete bacteria shown in last month's Video gallery.
The web video clips have to be compressed to keep the files small so
losses cf. the original video are inevitable.To view the video clips an
'avi' plugin must be installed in your web browser.
|Video clip left 152kB, avi format. Four
seconds at 5 frames/second, continuous loop. Taken using darkfield illumination.
This first video clip shows the cilia movement of a ciliated species of protozoa. The cilia are tiny beating hairs often of different length which are used in locomotion and for catching food. The water currents created bring food to the protozoa for ingestion.
Notice the collapsing contractile vacuole in the lower middle of the frame. These periodically form within the protoplasm, swell with water, contract and collapse. They discharge the water collected to the outside of the cell and are used to control the osmotic balance in the cell.
|Video clip left 86kB, avi format. Two
seconds at 5 frames/second, continuous loop. Taken using phase contrast
This second video clip shows the extending pseudopod of a protozoan like an Amoeba. The granular contents of the protoplasm are seen as the protozoan moves forward.
Comments to Edward Cowen welcomed.
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