172 ANIMAL COLORATION. 



pigment or to its increase. The field of hypotheses has- 

 no limits ; what we want is more study of the actual pigments 

 and their formation. 



The Wings of some Inedible Butterflies resist Injury. 



The immunity of gaudily-coloured, slow-flying butterflies- 

 is not always due entirely to their uneatable qualities. 

 Mr. Trillion has pointed out that the wings of these insects 

 have often a very elastic structure, and can endure very 

 rough treatment without serious injury ; in this way they 

 can frequently recover from the mistaken attacks of inex- 

 perienced foes. Looked at from this point of view, the 

 strength of the wings is merely an additional protection, 

 like the nocturnal habits of many protectively-coloured cater- 

 pillars. It may also have another meaning, which is not 

 suggested by Mr. Poultou. 



The wings call attention to the distastefulness of the insect ;. 

 they are the danger signal, and it is highly important that 

 they should be kept intact if possible ; a large piece bitten 

 out of the wing by a lizard or a bird in the hastiness of youth, 

 would not only impair the wings as organs of flight, but would 

 diminish their efficacy as danger flags by reducing their size; 

 the next animal that passed by would be less impressed by the 

 warning coloration, and might kill the insect. Mr. Skertchly 

 considers that nauseous insects are often very strong and 

 less easily injured ; the experiments with the caterpillars of 

 the Magpie moth and Buff-tip caterpillars (pp. 164, 165), quite 

 bear out this opinion. 



Dr. Eisig's Theory of Warning Colours. 



The suggestions of Dr. Eisig* seem to afford a more reliable 

 clue to the phenomena of warning colours ; his suggestions 

 * Die CapitelMen, " Naples Monographs." 



