. Contributions to the study of the behavior of lower organisms. Physiology, Comparative; Infusoria; Amoeba; Irritability. REACTIONS TO STIMULI IN CERTAIN ROTIKERA. S7 turning is continued still farther, so that the head of the animal de- scribes a complete circle ; indeed, this may continue so that the animal whirls around several times, always towards the dorsal side. The reaction thus far is the same as that produced by heat (Fig. 28). In reacting to the electric current the whirling finally ceases with ante-. FiG. 29.* rior end directed toward the new cathode. The animal then swims forward
. Contributions to the study of the behavior of lower organisms. Physiology, Comparative; Infusoria; Amoeba; Irritability. REACTIONS TO STIMULI IN CERTAIN ROTIKERA. S7 turning is continued still farther, so that the head of the animal de- scribes a complete circle ; indeed, this may continue so that the animal whirls around several times, always towards the dorsal side. The reaction thus far is the same as that produced by heat (Fig. 28). In reacting to the electric current the whirling finally ceases with ante-. FiG. 29.* rior end directed toward the new cathode. The animal then swims forward in the direction so indicated. These turnings, even when several times repeated, require but a moment, so that very soon prac- tically all the specimens are swimming toward the new cathode. The *FiG. 29.—Diagram of method by which Anuraea becomes oriented to rays of light, or to the electric current. Taking the latter for example, the animal is at first swimming toward the cathode, in direction indicated by arrow a;; it thus follows a spiral path from a to i>. At b the electric current is reversed. The animal thereupon swerves strongly toward its dorsal side, describing a semicircle, b, c, <i, until its anterior end is directed toward the new cathode, in the opposite direction from before. It now follows the spiral path d to , in the general direc- tion indicated by the arrow j*. The facts are similar for the reversal of light, or for the reaction when the current or the light is first set in 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. Washington : Carnegie Institution of Washington
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiol, bookyear1904
