PROTECTIVE MIMXCKY. 197 



all observers who have studied these groups." lu view of this 

 statement, which certainly expresses the general opinion, it is 

 snrjirising to learn from Dr. Seitz that this is by no means the 

 case invariably — even with the species referred to by previous 

 writers. Dr. Seitz tested as many as fifty species of Danaids, 

 both African and American, but could not recognise the least 

 odour, disagreeable or otherwise : and a number of these 

 S])ecies were models for mimicry. It is clear, therefore, that 

 every one interested in the subject must test this matter for 

 himself and form his own opinion. 



Distastefulness sometimes limited to a Few Individuals. 



In some, but not in all, Heliconids Dr. Seitz found an 

 odour decidedly objectionable to human nostrils, which he 

 compares to that of naphthalin. In Hdicoiiius beskii, a 

 species with a particularly evil odour, it was found that only 

 a few individuals were odoriferous, as is also the case with 

 our common lacewing fly, Chn/sopa. If the odour is as 

 objectionable to birds and lizards as it is to us, it looks as 

 if the majority traded on the unpleasant reputation of the 

 few ; and that the odour is not persistent, but depends upon 

 some variable circumstance, such as food. 



Resistent Structure of the Wings in Danaids an Additional 



Defence. 



The elastic structure of the wings in conspicuous butterflies 

 which My. Trimen first noticed, is a highly interesting fact. 

 Tlie wings are often so flexible that tliey can be bent without 

 breaking. 



Dr. Seitz has remarked in Tropical America that a species 

 of Acneii, is constantly found with its wings much rubbed, 

 with the scales hirgely removed. He attributes this to the 



