. Contributions to the study of the behavior of lower organisms. Physiology, Comparative; Infusoria; Amoeba; Irritability. THE MOVEMENTS AND REACTIONS OF AMCEBA. 165 MOVEMENTS OF THE POSTERIOR PART OF THE BODY. In an AmcEba moving as a simple, elongated mass, the anterior por- tion of the boily is broadest and very thin, being flattened against the substratum, while the posterior part is narrower and much thicker. In many cases the posterior end rises to an actual hump, the body being thickest at the posterior edge, or a little in front of this edge (Figs. 44, 5S). This is true as well of the
. Contributions to the study of the behavior of lower organisms. Physiology, Comparative; Infusoria; Amoeba; Irritability. THE MOVEMENTS AND REACTIONS OF AMCEBA. 165 MOVEMENTS OF THE POSTERIOR PART OF THE BODY. In an AmcEba moving as a simple, elongated mass, the anterior por- tion of the boily is broadest and very thin, being flattened against the substratum, while the posterior part is narrower and much thicker. In many cases the posterior end rises to an actual hump, the body being thickest at the posterior edge, or a little in front of this edge (Figs. 44, 5S). This is true as well of the Amoebae of nearly constant form {A. verrucosa^ etc., Fig. 44), as of those related to A. protetis. From this hump the upper surface slopes forward to the thin anterior edge. The margins in the posterior part of the body are not thin, but rounded like the surface of a cylinder. The anterior portion of the Amoeba is attached to the substra- tum. This attachment of the ante- rior portion has been clearly demon- strated by Rhumbler (1S9S), and I can confirm his results The attachment is probably by a mucus-like secretion ; at least such a secretion exists, as Rhumbler and others have shown and I can confirm. I have sometimes been able to pull an Amccba about by using a glass rod to which a thread of this mucus had become attached (Fig. 55). The animal then seems to follow the rod at a distance, the thread of mucus not being visible. In virtue of this attachment the Amoeba resists currents of water, or the impinging of solid bodies against it. The posterior portion of the body is not thus attached, but is entirely free from the bottom. In many cases the most posterior part of the body forms a more or less distinctly marked oft' portion, the surface of which is wrinkled or warty or villous, or otherwise irregular. This is variously known as the tail, the villous patch, or appendage (Wallich, Leidy), houppe (Penard), Schopf (Rhumbler), etc. The occurrence of this appendag
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