. Behavior of the lower organisms. Animal behavior; Invertebrates. B -. Fig. 68. — Interference of chemicals with the reaction to the electric current. At A Para- mecia have gathered in an area containing C02. At B an electric current is passed through the preparation with cathode at the left; the animals gather at the left edge of the area of C02- At C the current has been reversed; the animals are therefore gathered at the right edge of the area. the Paramecia are one by one caused to cross the boundary of the acid area and to swim to the cathode. If a drop of some repellent chemical — as so
. Behavior of the lower organisms. Animal behavior; Invertebrates. B -. Fig. 68. — Interference of chemicals with the reaction to the electric current. At A Para- mecia have gathered in an area containing C02. At B an electric current is passed through the preparation with cathode at the left; the animals gather at the left edge of the area of C02- At C the current has been reversed; the animals are therefore gathered at the right edge of the area. the Paramecia are one by one caused to cross the boundary of the acid area and to swim to the cathode. If a drop of some repellent chemical — as sodium chloride or an alkali — is introduced into a preparation (Fig. 41), the Paramecia of course leave this vacant. If the electric current is passed through the preparation, the Paramecia swim toward the cathode; coming to the boundary of the drop, they swim around it, leaving it empty, and thus reach the cathode. In this case the path followed is a resultant of the operation of the two stimuli, — the orienta- tion due to the electric current and the avoiding reaction produced by the chemical. If the entire region next the cathode is occupied by a repellent chemi- cal, the Paramecia may be forced by a strong and long-continued cur- rent to enter it till they are destroyed. A very peculiar interaction of chemicals and the electric current is seen when Paramecia are placed in physiological salt solution ( per. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Jennings, H. S. (Herbert Spencer), 1868-1947. New York, The Columbia university press, The Macmillan company, agents; [etc. , etc. ]
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