THE SHAPES OF BIRDS 263 



as soon as we learn all the habits of the creature in 

 question we shall see how perfectly its colour is adapted 

 to its mode of life. This may be so. Nevertheless this 

 kind of argument is not scientific. It tends to stifle 

 inquiry, which is the true spirit of science. 



The fact is that natural selection is a horse ridden to 

 death. It is indisputably a most important factor in 

 organic evolution, but are we justified in regarding it as 

 the only factor? It is unable, I think, to explain many 

 natural phenomena. One of these is the varying shapes 

 of nearly allied animals. 



Certain it is that the general form of a class of 

 organisms is determined by natural selection, but are 

 the thousand and one shapes seen among closely related 

 creatures all to be explained by saying that were these 

 of any other form they would perish in the struggle for 

 existence ? 



Birds afford a striking example of the many shapes 

 which may be assumed by creatures of very similar 

 habits. I recently visited the Nilgiris, and spent many 

 hours in a wood which might appropriately be called 

 " The Flycatchers' Wood." No fewer than five species 

 of that family are common in the wood of which the 

 area is less than 5000 square yards. All these species 

 have very similar habits. 



To enumerate them. There is first the white-browed 

 fantail flycatcher {Rhipidura albifrontatd), a bird too 

 well known to need detailed description. It will suffice 

 that its chief characteristic is the tail, which it continu- 

 ally spreads out into a fan. This appendage is about 

 three and a half inches long, that is to say, equal in 



