. Behavior of the lower organisms. Animal behavior; Invertebrates. Fig. 114. — Spontaneous changes of positions in an undis- turbed Hydra. Side view. The extended animal (1) contracts (2), bends to a new position (3), and then extends (4). Fig. 115. — Dia- gram of different posi- tions taken by Hydra, as seen from above. After Wagner. This is apparently correlated with the fact that the yellow Hydra has very long tentacles, which lie in coils all about it, so that exploratory movements are not necessary in order to reach such food as may be found in the neighborhood. If a green Hydra is left f
. Behavior of the lower organisms. Animal behavior; Invertebrates. Fig. 114. — Spontaneous changes of positions in an undis- turbed Hydra. Side view. The extended animal (1) contracts (2), bends to a new position (3), and then extends (4). Fig. 115. — Dia- gram of different posi- tions taken by Hydra, as seen from above. After Wagner. This is apparently correlated with the fact that the yellow Hydra has very long tentacles, which lie in coils all about it, so that exploratory movements are not necessary in order to reach such food as may be found in the neighborhood. If a green Hydra is left for long periods undisturbed, it does not remain attached in the same posi- 1 tion, but moves about from place to place. The movements often take place in random directions, — the animal starting first in one direc- tion, then in another. Figure 116 shows the movements of a green Hydra, which was left alone for some days in the bottom of a large, clean glass dish, the light coming from a window at the right. This move- ment is probably brought about by Fig. followed by a green hunger — the animals taking a new Hydra that was left for some days undisturbed position when food becomes Scarce. on the bottom of a clean glass dish. After £L , . 1 Wagner (1905). Hydra may move about in several. 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. ]
Size: 1528px × 1635px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectanimalbehavior, booky
