If, during the observation, a small crystal of salt be placed in the fluid, changes almost instantly take place.

Motion ceases, the amoebae appear to shrink into smaller compass, and they become more granular and opaque.

If they remain a sufficiently long time in this fluid, they do not regain their usual condition when placed again in fresh water.

None of the phenomena which characterized the living amoebae appear: we say they are dead.

After a time they begin to disintegrate, and the bacteria contained in the water and on which the amoebae fed now invade their tissue and assist in the disintegration.