Movements.—Sometimes while the pseudopods are being extended and contracted, the central portion remains in the same place (this is motion). Usually only one pseudopod is extended, and the body flows into it; this is locomotion (Fig. [11]). There is a new foot made for each step.
Feeding.—If the amœba crawls near a food particle, the pseudopod is pressed against it, or a depression occurs (Fig. [12]), and the particle is soon embedded in the endoplasm. Often a clear space called a food vacuole is noticed around the food particle. This is the water that is taken in with the particle (Fig. [12]). The water and the particle are soon absorbed and assimilated by the endoplasm.
Fig. 12.—The Amœba taking food.
Excretion.—If a particle of sand or other indigestible matter is taken in, it is left behind as the amœba moves on. There is a clear space called the contractile vacuole, which slowly contracts and disappears, then reappears and expands (Figs. [9] and [10]). This possibly aids in excreting oxidized or useless material.
Circulation in the amœba consists of the movement of its protoplasmic particles. It lacks special organs of circulation.
Feeling.—Jarring the glass slide seems to be felt, for it causes the activity of the amœba to vary. It does not take in for food every particle that it touches. This may be the beginning of taste, based upon mere chemical affinity. The pseudopods aid in feeling.
Reproduction.—Sometimes an amœba is seen dividing into two parts. A narrowing takes place in the middle; the nucleus also divides, a part going to each portion (Fig. [13]). The mother amœba finally divides into two daughter amœbas. Sex is wanting.
Fig. 13.—Amœba, Dividing.