428 PACKARD— ORIGIN OF MARKINGS OF ORGANISMS. [Dec. 2, 



parts of the world, green or brown, imitating green or dead leaves 

 and living among foliage, while others hide in holes and under 

 logs. '* All these come out only at night to feed, and they are all 

 preyed upon by snakes and birds." But the single inedible species 

 is conspicuously marked with red and blue, and it is a significant 

 fact that it hops about in the daytime. It is apparently to this 

 habit of living in the hot sunlight that the color markings of this 

 frog owe their origin, driven perhaps by competition to the 

 necessity of seeking insects in broad daylight. The sunlight and 

 moisture of the Nicaraguan climate is perhaps with little doubt the 

 cause of the deposition of a larger amount of pigment than in the 

 other species ; it is consequently more concentrated and acrid or 

 nauseous, and thus repugnant to birds. We know that toads are 

 not eaten so readily as frogs, owing to the acrid secretion from 

 their skin. The Nicaraguan frog then, as a result of an original 

 change in habit, became permanently diurnal, consequently the 

 more abundant pigment, varying in thickness and density on differ- 

 ent parts of its body, made it gayly banded and .<?potted, so that 

 birds learned to avoid it. The result is that by selection, if one 

 pleases, the species becomes established and preserved, so long as 

 the natural conditions of existence remain unaltered. But we sub- 

 mit that the primary or initial causes or factors in the evolution of 

 the so-called warning colors and taste are the result of exposure to 

 the direct sunlight, and consequent excessive pigmentation ; the 

 food also being more abundant, as the other species are hidden 

 away ; finally we will allow that the species are preserved by what is 

 called natural selection, though we grant this with the proviso that 

 natural selection is powerless to act and entirely wanting and 

 insufficient should a change of conditions, physical, climatic and 

 biological, supervene to change the creature's habits. And so it is 

 with the bitter-tasting butterflies and their conspicuous colors and 

 markings ; their light-loving habits and a hot, moist climate are the 

 causes of modification — causes which cannot be overlooked or 

 ignored. 



9. Protective Mimicry not Necessarily Applicable to Snakes. 



O. Boettger,^ as the result of the examination of a collection from 

 Brazil, finds that the prevailing colors are red, black and white or 



1 Bericht d. Senckenberg. Naturforsch. Ges., 1899, pp. 75-88. Also 

 Journ. Roy. Micr. Soc, 1900, p. 311. 



