Page:Popular Science Monthly Volume 31.djvu/829

Rh Caton's experiment. The same writer has also observed in the Hawaiian Islands the effects of reversion to a wild state of different kinds of domestic animals which have from time to time been carried there. Among other animals he was fortunate enough to observe the undoing stages in the domestic turkey and the assumption of those features which characterize the wild bird.

A great many facts illustrating the plainest features of natural selection, protective coloring, mimicry, etc., have been recorded in our journals from time to time. A brief allusion may be made to a few of these.

Professor Samuel F. Clarke notices a pronounced case of natural selection, a case which must often occur in nature. He kept in large glass jars masses of eggs of Amblystoma. As soon as these eggs began to hatch he found it difficult to provide the young with suitable food, and yet they seemed to thrive. On examination, many of them were seen to be engaged in nibbling the branchia of others, and as they increased in size they were seen to swallow the weaker individuals bodily and hence grow with increased rapidity. "Here, then," he says, "was a very interesting case of natural selection by survival of the fittest, all the weaker individuals being destroyed and actually aiding the stronger ones by serving them as food until they could pass through their changes and escape to other regions where food was more abundant." Professor B. G. Wilder has recorded a similar condition of things in a species of spider where the young spiders within the case inclosing the eggs were feeding on the weaker ones. Professor Henry L. Osborn observes a curious case of mimicry at Beaufort in the coloring of a species of Ovulum which frequents a species of Leptogorgia. The Ovulum was yellow in color on the yellow variety of this sea-fan, and purple when living on the purple variety. Dr. R. E. C. Stearns has made some interesting notes on protective coloring in Phrynosomæ. Having collected these horned lizards (or toads as they are commonly called) in Central California, he has noticed that if the ground region they frequent is yellowish, the lizards are without exception of that color; if ashen-gray, then that color is simulated, and this without exception. Further than this he is "led to believe that a sufficient number of living specimens will show a similar protective factor in degree of development of the scale imbrications, tubercles, so called, and horns—or, in brief, in the sculpture aspect as related to the surface texture of the ground which forms the local habitat of these forms." Dr. A. S. Packard has observed the partiality of white butterflies for white flowers. He notices the European cabbage-butterfly, which is white, go directly to the white aster and rarely visit the golden-rod; while the yellow sulphur butterfly