Address on Colors of Animals.

Mr. Edward B. Poulton, M. A., F. R. S., of the University of Oxford, gave a most interesting lecture yesterday afternoon under the auspices of the Natural History Society, on the subject: "Some Recent Investigations upon the Meaning and Use of the Colors of Animals in the Struggle for Existence." The lecture included some of the most interesting parts of the course which Mr. Poulton has recently given at the Lowell Institute and was elaborately illustrated throughout by the stereopticon.

Mr. Poulton first spoke of the color of animals as adapted to purposes of concealment. This adaptation, he said, goes beyond merely affecting the surface of the animal's body and is deep seated in the nervous system. Some insects closely resemble dead leaves, and as a dead leaf with a hole in it appears more decayed than one that is entire, so some insects go to the extent of having what gives the impression of a hole upon the surface of their bodies. In one stage of development this hole is represented, as an artist would represent it on canvas, by a white spot, but in a more advanced stage, the spot becomes actually transparent.

The common colors of nature are green and brown, and hence most insects are of one or the other of these two colors. It has been a question whether the color of insects was derived directly from the coloring matter of their vegetable food, or whether it was due to some peculiar process which had nothing to do with the color of food. Experiments made upon larvae with food material of different colors has shown conclusively that the color of the insect is affected by the color of its food.

With reference to the power of changing colors, there is some variety in different animals. This power naturally varies with the needs of each animal. One that lives in a locality of comparative uniform color requires less power of change than one that lives in a varied locality. A number of interesting pictures were shown by the stereopticon, illustrating the effects of different colored localities upon different larvae. In nearly every case there was a marked imitation of the surface of the plant or tree on which the larvae lived.

Colors are sometimes assumed by animals for purposes of warning, that is for keeping off the animals that are natural enemies. This is done either by a feigned resemblance to an animal of a different and often dangerous kind, or by an appearance of being wounded and therefore useless to an enemy. Pictures were shown of hermit-crabs, which attached to themselves sea-anemonies for the purpose of self-defence, the anemonies being offensive to hostile fishes. One picture represented a deep-sea fish which attracts its prey by a lure in the shape of a phosphorescent light; another showed a snap-turtle which lies for hours with its mouth open and entices small fish by means of filaments on its tongue which look like worms.