| Themes > Science > Zoological Sciences > Animal Phyla and Included Classes > Sub-Kingdom: Protozoa > Phylum Rhizopoda |
If available, obtain a drop of living Amoeba culture. Do not use strong light. Amebae may be difficult to distinguish at first, because of their indefinite shape, but can be differentiated from amorphous "globs" by the smooth body outline, and slow steady movement. The outer portion (ectoplasm) is clear. The inner portion (endoplasm) is dense and granular. Irregular food vacuoles may be seen, also contractile vacuoles which increase in size, and suddenly disappear, discharging water to the exterior. There is no special site of elimination of waste from the food vacuoles. Some of the same structures, plus the cell nucleus may be seen on the stained slide. Amebae divide asexually by simple fission. This common type inhabits fresh water. There is also a very important parasitic ameba, (Entameoba histolytica), which causes acute diarrhea and ulcerated intestinal tract infections. Like the flagellates, most Sarcodina can encyst. |
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