28 COSMIC PHILOSOPHT. [pt. ii 



of the elaT3orate observations which have led to these con- 

 clusions. "Without feeling it necessary to insist upon the 

 validity of all the special explanations contained in that 

 work, we must admit that the general theory is substantiated 

 by a superabundance of inductive evidence. And wlien Ihia 

 kind of selection is taken in connection with the need foi 

 protective concealment, we have the means of explaining by 

 far the greater part of the colouring found in the animal 

 kingdom. 



The colours of the vegetal kingdom have, to a considerable 

 extent, been no less satisfactorily explained. "Flowers do 

 not often need protection, but very often require the aid of 

 insects to fertilize them, and maintain their reproductive 

 powers in the greatest vigour. Their gay colours attract 

 insects, as do also their sweet odours and honeyed secretions; 

 and that this is the main function of colour in flowers is 

 shown by the striking fact that those plants which can be 

 perfectly fertilized by the wind, and do not need the aid of 

 insects, rarely or never have gaily-coloured flowers."^ 



Eeturning for one moment to the case of animals, which 

 are usually benefited by concealment but sometimes by 

 conspicuousness, let us note Prof. Shaler's ingenious explana- 

 tion of the rattlesnake's rattle. The existence of this 

 appendage has long been a puzzle to philosophical naturalists, 

 and Darwinians have been repeatedly challenged to account 

 for the formation or preservation by natural selection of an 

 organ assumed to be injurious to the species. The difficulty 

 has lain in the assumption, too hastily made, that the noise 

 of the rattle must be prejudicial to the snake by fore- 

 warning its enemies or prey of its presence, and thua 

 eiviuCT the enemies time for sudden attack, and allowin2 

 the prey to escape. On the theory of natural selection, the 

 preservation of the species must entail the atrophy of such 

 an organ, or, rather, must prevent its origination, unless the 

 * Wallace, Natural Selection, p. 262. 



