THE RELATION BETWEEN KIND OF FOOD, GROWTH, AND STRUCTURE IN AMOEBA

¹ From the Zoölogical Laboratory of the Johns Hopkins University and the Marine Biological Laboratory, Woods Hole, Mass.

1. If specimens of Amoeba proteus are fed exclusively on colpidia, they become very large and extremely fat and sluggish and grow and multiply slowly, but indefinitely. The refractive bodies in them decrease greatly in number and size and their content becomes homogeneous and very adhesive, elastic and viscous. The crystals decrease in number and become shorter and more truncated.

2. If they are fed exclusively on chilomonads, they grow and multiply for several days, then decrease in number and soon die, but they live longer if the chilomonads have grown in glucose-peptone solution than if they have grown in acetate-ammonium solution. The refractive bodies increase greatly in size and number and the content of these bodies becomes sharply differentiated; the bipyramidal crystals increase in number and become less truncated, and the fat decreases in quantity.

3. If specimens of Amoeba dubia feed exclusively on chilomonads, they multiply for a few days, then cease and soon die. The irregular-shaped crystals increase and the plate-like crystals decrease considerably in number and the fat disappears.

4. If they feed exclusively on colpidia, they multiply more and live longer than if they feed exclusively on chilomonads, but they do not live indefinitely. The plate-like crystals increase in number and the irregularly shaped crystals usually disappear entirely and the fat increases in quantity, but not so much as it does in Amoeba proteus.

5. Amoeba is in reference to form, size, behavior, and structure closely correlated with the kind of organisms it eats and their physiological condition.