2IO DARWINISM AND THE PROBLEMS OF LIFE 



skin cannot be stimulated by the pressure to form 

 stronger parts, since its function ceased at the last 

 cast of the skin. 



In the same way we find many other co-adaptations 

 in the coats of bees, wasps, butterflies, etc., in which 

 the last cast is the abandonment of the pupa-skin, when 

 they first receive their specific features, such as wings 

 and so on. Hence when we find on the fore-legs of 

 bees and wasps certain structures consisting of two 

 parts forming a ring with teeth in its inner side, through 

 which the antennae are drawn to be cleaned, we have a 

 structure that cannot have arisen by use. The same 

 may be said of the mouth -parts of these insects. In 

 the gnat there are at least eight parts that are all 

 modified in the same sense as stabbing - bristles and 

 suctorial apparatus ; they are all about the same length, 

 and can only act in conjunction. The antlers of the 

 large stag with the thick skull and the proportionately 

 modified other parts are not more wonderful than the 

 parallel development of the mouth-parts of the gnat. 

 When the Lamarckian principle is admitted on the 

 ground that it is said to meet difficulties that natural 

 selection cannot explain, we s^e that this is not the case. 

 At all events, it does not do away with the difficulty of 

 co-adaptations, because there are co-adaptations that it 

 cannot explain. 



But are co-adaptations really inexplicable by natural 

 selection ? Selectionists say they are not, and they 

 are quite right. In the first place, artificial selection 

 shows that harmonious variations do actually take place. 

 Think of the dachshund, which has been brought to its 



