Page:A Text-book of Animal Physiology.djvu/43

inorganic and unorganized food, also organized matter in the form of a complex organic compound known as protein, which contains nitrogen in addition to carbon, hydrogen, and oxygen. In fact, Amœba can prey upon both plants and animals, and thus use up as food protoplasm itself. The pseudopodia serve the double purpose of organs of locomotion and prehension.

Figs. 8 to 16, represent successive phases in the life-history of an Amœboid organism, kept under constant observation for three days; Fig. 16 a similar organism encysted, which was a few hours later set free by the disintegration of the cyst. (All the figures are drawn under Zeiss, D. 3.)
Fig. 8.—The locomotor phase; the ectoplasm is seen protruding to form a pseudopodium, into which the endoplasm passes. Fig. 9.—A stage in the ingestive phase. A vegetable organism, fp, is undergoing intussusception.
Fig. 10.—A portion of the creature represented in Fig. 9 after complete ingestion of the food-particle.
Figs. 11, 12.—Successive stages in the assimilative and excretory processes. Fig. 12. represents the organism some twenty hours later than as seen in Fig. 11. The undigested remnants of the ingested organism are represented undergoing ejection (excretion) at fp in Fig. 12.
Figs. 13, 14, 15, represent successive stages in the reproductive process of the same individual, observed two days later. It will be noticed (Fig. 13) that the nucleus divides first.
In the above figures, vc, denotes the contracting vacuole; nc, the nucleus; ps, pseudopodium; dt, diatom; fp, food-particle.

This creature absorbs oxygen and evolves carbon dioxide.