278 



THE AMERICAN NATURALIST [Vol. LI 



points which his opponent had failed to take into con- 

 sideration. 



It may be added that Marshall's reasoning rests upon 

 what is without much doubt a baseless assumption, for he 

 follows Miiller in postulating that two species of distaste- 

 ful insects will lose the same absolute number of indi- 

 viduals through attacks of ignorant enemies'which in the 

 beginning recognize neither of them. As a matter of fact, 

 if two species differing in no res]XH't except appear- 

 ance are represented in the same area by lOO.OUO and 

 5,000 individuals, respectivolx , Mni^li.ill ii^Minies, the 

 chances are 20: 1 that any animal iiiakiiiu' an independent 

 test of the food resources of its enN ii'oiimciit would first 

 meet the more abundant form, l^niess it learns its lesson 

 perfectly from a single experience, the chances are essen- 

 tially the same that it will kill another butterfly of the same 

 kind before it encounters one of the second distasteful sort. 

 But if most inexperienced enemies learn at the expense 

 of one sj)ecies that some butterflies arc not edible, it 

 is scarcely to be supposed that they will undergo as 

 many unj)leasant exi)eriences before they retain an im- 

 pression of the disagreeable character of the other. 

 Hence Marshall's criticism can not be considered at pres- 

 ent a valid objection. 



Packard*'"^ believed that llic (•(.iiccpt of M iillei ian mimi- 



cumulating so many exaniplo <,t" warning coloration in 

 their "Bionomics of South Afi-ican Insects" ]VIarshall 

 and Poulton" in particular attempted to prove too much. 

 Why an association of some scores of species represent- 

 ing many orders of Maslionaland insects should be pivoted 

 ui)on the bitter-flavored beetle, Li/cns, tliough some mem- 

 bers of the group seemed more amply protected from at.^ 

 tack by birds and lizards, was not clear. Yet one dare 

 not be (loyniatic in such matters, for the wasp, Po. 

 tliouiili iiKiic ail('(|iiately equipped for defense ' 

 otluT iik'IiiIkt <»t' the association, may have drift* 



