Toxic solutions applied at one end of a Nitella cell 6 cm. long may produce little or no visible change in the structure of the protoplasm at the place of application but if the opposite end is covered with water its protoplasm soon disintegrates. If the middle of the cell is covered with mineral oil this region remains normal in appearance for half an hour or more.
The result is due to the movement of substances in the cell. The loss of substances at the end where the toxic agent is applied results in loss at the opposite end if it is covered with water since water enters and travels along inside the cell carrying substances with it. This causes injury at the spot where the water enters.
The conception developed here differs fundamentally from the usual view that the effects of injury spread gradually from the region where the toxic agent is applied to the immediately adjoining regions and thence to more remote places.
The change produced by loss of substances produces an interesting pattern which deserves study.