AMERICAN ZOOLOGISTS AND EVOLUTION. 809 



Caton's experiment. The same writer* has also observed in the Ha- 

 waiian 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 se- 

 lection, 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 f 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 be- 

 gan 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 individu- 

 als 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 con- 

 dition of things in a species of spider where the young spiders within 

 the case inclosing the eggs were feeding on the weaker ones. Pro- 

 fessor Henry L. Osborn \ observes a curious case of mimicry at Beau- 

 fort in the coloring of a species of Ovulum which frequents a species 

 of Leptogorgia. The Ovulum was yellow in color on the yellow vari- 

 ety of this sea-fan, and purple when living on the purple variety. Dr. 

 R. E. C. Stearns # has made some interesting notes on protective col- 

 oring in Phrynosomm. Having collected these horned lizards (or 

 toads as they are commonly called) in Central California, he has no- 

 ticed 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 imbri- 

 cations, 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 Euro- 

 pean cabbage-butterfly, which is white, go directly to the white aster 

 and rarely visit the golden-rod ; while the yellow sulphur butterfly vis- 



* " American Naturalist," vol. xv, p. 955. f Ibid., vol. xii, p. 615. 



\ " Science," vol. vi, p. 9. 



w " American Naturalist," vol. xvii, p. 1077. [| Ibid., vol. xi, p. 243. 



