Dissection and injection studies on the Amœba

The species used was Amœba proteus. By means of a micropipette liquids of various kinds were injected and the effect noted.

Oils form spherical droplets which are carried about in the cytoplasmic currents. A large drop is usually expelled. Immediately on being extruded the drop tends to flow over the surface of the Amœba thus partially engulfing it.

Distilled or spring water diffuses through the granular endosarc diluting it. The dilution is followed by a contraction of the endosarc and the massing of a hyaline fluid between the endosarc and the external pellicle of the Amœba. This dilates the area usually termed the ectosarc. The fluid soon accumulates on one side of the Amœba in the form of a blister which is ultimately pinched off.

A number of acid indicators were injected. The color reactions showed that the protoplasm of the Amœba is more acid than its environment. Upon death the colors change to those characteristic of the surrounding medium.

The difference in behavior of living protoplasm to “basic” and to “acid” dyes is striking. The “basic” dyes used were all chlorides of colored basic radicles and the “acid” dyes, potassium or sodium salts of colored acid radicles. In every case the “basic” dyes had a coagulating and the “acid” dyes, a liquefying effect on the protoplasm.

In the case of the “acid” dyes, when the effect is local, the healthy non-colored portion of the endosarc shrinks away from the colored liquefied area. This liquid accumulates under the pellicle in the form of a blister and is ultimately pinched off.

If the “basic” dye be relatively nontoxic its injection results in a coagulated area which is localized as a colored lump of inert material. This lump is carried about in the protoplasmic currents.