288 Darwin, aiid after Darivin. 



upon no other theory can its universality and invari- 

 ability be rendered intelligible. On the beneficent 

 design theory, for instance, it is inexplicable that no 

 species should ever be found to present a structure or 

 an instinct having primary reference to the welfare of 

 another species, when, ex hypothesi, such an endless 

 amount of thought has been displayed in the creation 

 of structures and instincts having primary reference to 

 the species which present them. For how magnificent 

 a display of divine beneficence would organic nature 

 have afforded, if all — or even some — species had been 

 so inter-related as to have ministered to each others 

 wants. Organic species might then have been likened 

 to a countless multitude of voices, all singing in one 

 great harmonious psalm. But. as it is, we see abso- 

 lutely no vestige of such co-ordination : every species 

 is for itself, and for itself alone — an outcome of the 

 always and everywhere fiercely raging struggle for 

 life. 



In order that the force of this argument may not be 

 misapprehended, it is necessary to bear in mind that 

 it is in no way affected by cases where a structure or 

 an instinct is of primary benefit to its possessor, and 

 then becomes of secondary benefit to some other species 

 on account of the latter being able in some way or 

 another to utilise its action. Of course organic nature 

 is full of cases of this kind ; but they only go to show 

 the readiness which all species display to utilise for 

 themselves everything that can be turned to good ac- 

 count in their own environments, and so, among other 

 things, the structures and instincts of other animals. For 

 instance, it would be no answer to Darwin's challenge if 

 any one were to point to a hermit-crab inhabiting the 



