1904.] PACKARD— ORIGIN OF MARKINGS OF ORGANISMS. 421 



Mimicry not primarily due to natural selection. — As has been 

 often stated by Semper and others, natural selection is not a trans- 

 forming agent, but rather results in the preservation of species. 

 With little doubt models and mimics resemble each other because 

 the light and background or environment are the same, and act on 

 great numbers of individuals in a given area. 



While Bates, and apparently Fritz Miiller, put forward their views 

 in a tentative way, later writers of the extreme Darwinian school, 

 notably Wallace, Poulton, Weismann, and a few others, strongly 

 insist on the entire sufficiency of the selection hypothesis, claiming 

 that it is the sole, primitive cause of the mimicry. Thus Prof. 

 Poulton^ goes so far as to claim that " birds are among the chief 

 enemies of butterflies," adding: ''That they have been the chief, 

 if not the only, agents in the production of mimicry, whether 

 Batesian or Mlillerian, "I have little doubt." Again he says: 

 "The intensely procryptic habits and colors of many nymphaline 

 genera have certainly been brought about by selection, due to the 

 great keenness and success of insect-eating animals in their pursuit." 



This conclusion does not harmonize with what appears to be the 

 fact that only a very limited number of birds in any country, tem- 

 perate or tropical, is as yet known to pursue butterflies, or that they, 

 with the exception of the bee-eater, use these insects as a staple 

 article of food. 



Bright colors not invariably associated with a nauseous taste or 

 odor. — While certain showy, brilliantly painted butterflies and 

 other less conspicuously marked species are known to have a dis- 

 agreeable taste or odor, there are multitudes of black or obscurely 

 marked beetles, bugs, etc., which are still more malodorous and 

 provided with '• stink-glands." Many more detailed observations 

 and anatomical investigations need to be made on the subject of 

 inedible Lepidoptera. The unpalatable nymphalid butterflies 

 (Ithomiinse, Danainse, Heliconinse and Acraeinse) apparently vary 

 in the nature and extent of the secretions. For nearly all that we 

 know of the occurrence of repugnatorial glands in Heliconid 

 butterflies we are indebted to Fritz Miiller, who detected in Colae- 

 nis, Heliconius, Eueides and Dione a pair of anal eversible glands 

 which give out a disagreeable odor, and which appear to be the 

 homologue of the odoriferous glands of butteiflies of other groups. 



1 Transactions Ent. Soc. London, 1 902, p. 356. 



l>ROC. AMER. PHILOS. SOC. XLIII. 17S. BB. PRINTED JAN. 21, 1905. 



