REPRESENTATIVE SPECIES. 87 



ditions of life ; so that we cannot doubt that the 

 varied colours resulting from the influence of 

 climate in the first place have been made the best 

 possible use of, and even intensified and elaborated 

 by the stimulating forces of selection. It must, 

 however, be clearly understood that such climatic 

 variation has only been so seized upon by Natural 

 Selection when it has come to be of service to 

 the species, and that in a very great number of 

 cases such variation is at present not of the slightest 

 service, and possibly may never be so. This colour 

 modification by climate removes some of the most 

 serious difficulties and objections to the theory of 

 Protective Resemblance. It disposes of the grave 

 difficulty of demonstrating how a species or race 

 could derive sufficient benefit in the struggle for 

 life from a scarcely perceptible difference in the 

 shade or tint of its plumage, to bring such differ- 

 ence within the scope of Natural Selection. Further, 

 it seems to me that other incipient modifications 

 (not of colour only) may arise in similar w^ays 

 from a variety of causes entirely unconnected with 

 the vital conditions of existence, and not be in- 

 fluenced in any way by selection until they have 

 become sufficiently pronounced and important to 

 be of use. 



