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



not see that Dr. Muller's explanations and calculations cleared up 

 all the difficulties. The numerous cases where species which are 

 themselves apparently protected by their offensive secretions evi- 

 dently mimic other species similarly protected still form a great 

 stumbling block. The excessive complexity of the question must 

 be evident to all who read Dr. Fritz Muller's writings on this sub- 

 ject. The phenomena with regard to the Heliconidae, stated 

 broadly, were these : In tropical South America a numerous series of 

 gayly-colored butterflies and moths, of very different families, which 

 occur in abundance in almost every locality a naturalist may visit, 

 are found all to change their hues and markings together, as if by 

 the touch of an enchanter's wand, at every few hundred miles, the 

 distances being shorter near the eastern slopes of the Andes than 

 nearer the Atlantic. So close is tlie accord of some half a dozen 

 species (of widely different genera) in each change that he (Mr. 

 Bates) had seen them in large collections classed and named respec- 

 tively as one species. Such a phenomenon was calculated to excite 

 the interest of the traveling naturalist in the highest degree. 

 Although the accordant changes were generally complete, cases 

 occurred in which intermediate varieties were still extant, and the 

 study of these had given him, when he was in South America, the 

 clue to an explanation which, however, does not embrace the whole 

 of the problem " (p. xxix). 



From the facts regarding these local varieties thus stated by 

 Bates, we seem warranted in ascribing the mimetic resemblances to 

 convergence, or exposure to the same conditions of light, heat, 

 moisture, etc., affecting all the individualsof a variety simultaneously, 

 rather than to what is vaguely called *' natural selection." A geo- 

 graphical series of each locality arranged in order from east to west 

 would graphically elucidate the problem. 



8. Criticisms of the Bates-Muller Hypotheses. 



The color and markings of animals in general are primarily due 

 to the action of light and the color of the environment or back- 

 ground. To suppose that in tlie case of butterflies alone the colors 

 of the mimics are due to the attacks of birds, whereas remarkably 

 few butterflies, as we have seen, are ever eaten by them, is a cause 

 so inadequate, so limited in its scope and so one-sided, that it is 

 no wonder the hypotheses has many opponents. 



