GERMINAL SELECTION. 51 



therefore, is now not compelled to wait for accidental 

 variations but produces such itself, whenever the re- 

 quired elements for the purpose are present. Now, 

 where it is a question simply of the enlargement or 

 diminution of a part, or of a part of a part, these varia- 

 tions are always present, and in modifications of qual- 

 ity they are at least present in many cases. 



This is the only way in which I can see a possibility 

 of explaining phenomena of mimicry — the imitation 

 of one species by another. The useful variations must 

 be produced in the germ itself by internal selection- 

 processes if this class of facts is to be rendered intel- 

 ligible. I refer to the mimicry of an exempt species 

 by two or three other species, or, the aping of different 

 exempt patterns by one species in need of protection. 

 It must be conceded to Darwin and Wallace that some 

 degre;e of similarity between the copy and the imita- 

 tion was present from the start, at least in very many 

 cases ;^ but in no case would this have been sufficient 

 had not slight shades of coloring afforded some hold 

 for personal selection, and in this way furnished a 

 basis for independent germinal selection acting only 

 in the direction indicated. It would have been im- 

 possible for such a minute similarity in the design, 

 and particularly in the shades of the coloration, ever to 

 have arisen, if the process of adaptation rested entirely 



1 That this is not so in all cases has recently been shown 

 by Dixey from observations on certain white butterflies of 

 South America which mimic the Heliconids and in which a 

 small, yellowish red streak on the under surface of the hind 

 wing has served as the point of departure and groundwork 

 of the development of a protective resemblance to quite 

 differently colored Heliconids. "On the Relation of Mimetic 

 Characters to the Original Form," in' the Report of the British 

 Association for 1894. 



