Irritation and Excitability

If you shine a ray of light on one section of a drop of water containing Amoebae, the animals will move to the darker side. This shows that they react to light and respond with physical movement.

If you introduce a crystal of table salt, the movements of the Amoebae will become slower, the pseudopodia will be drawn in, and the animals will assume a rounded shape. This means, the Amoebae react to salt and respond by changing their shapes.

Experiments have shown that among agents affecting the Amoebae, apart from light and salt solutions are food, warmth, and oxygen. Under the influence of these and other stimuli sensitivity is produced in the protoplasm of the Amoeba (and other animals as well). The animal reacts to the stimulation with physical movement.

This physical response makes it possible for the animal to adapt itself to changes in its surroundings. Bright light means death, so the Amoebae move into dark places. By drawing in their pseudopodia they diminish the area of the body surface exposed to the harmful effects of the salt solution.

Reproduction

The amoeba multiplies by simply dividing into two. It takes an oblong shape, its nucleus divides into two portions, and the portions part. A 'waist' appears in the protoplasm, which becomes narrower. Finally, the body of the "mother" Amoeba separates into two smaller "daughters".

Encystment

If the reservoir dries out the body of the Amoeba takes on a round shape and is covered with a tough wall. This wall is called a cyst. In this condition the Amoeba easily withstands not only lack of moisture but also frost. As soon as the cyst is again surrounded by water, the wall bursts and the Amoeba come out.

Dysenteriae

The Common Amoeba is harmless to man. Even if it gets into his intestine in dirty water, it is easily digested. The Dysenteriae are different. They attack the intestinal walls causing bleeding ulcers. Amoebic dysentery may cause death to man. Infection may result from drinking unboiled water from sources contaminated by the excreta of people suffering from amoebic dysentery.

Tasks

1. Write down whether the following statements are true or false. Give extensive answers.

1. The common Amoeba moves slowly by means of pseudopodia on the top of the fresh-water ponds.

2. The Amoeba is a tiny blob of mucus, regular in form.

3. In Greek, the word “amoibe” means “change” because as it moves, the shape of the Amoeba’s body constantly changes.

4. The Amoeba has to move fast to obtain food.

5. The Amoeba respires in the same way as the Paramecium.

6. The Amoebae don’t react to anything.

7. The physical response makes it possible for the Amoeba to adapt itself to changes in its surroundings.

8. The body of the “mother” Amoeba separates into several small parts.

9. The Amoeba can’t withstand lack of moisture.

10. The Common Amoeba may cause death to man.

2. Complete the sentences using the text and translate them into Russian.

1. The Common Amoeba moves slowly by …

2. The Amoeba is a …, like …

3. … parts of its body are pushed out …

4. … and gradually draws it inside.

5. … is used to build up…

6. … oxygen, …, easily passes into …

7. From time to time, the vacuole …

8. … among agents affecting the Amoebae, …

9. By drawing in their pseudopodia they …

10. As soon as …, the wall bursts and the Amoeba comes out.