EXTINCT SPECIES. 141 



If logical proof in syllogistic form be demanded as to the 

 proposition that laws established by Nature have no excep- 

 tions, the fulfilment of demand would not be possible, inas- 

 much as human reason is too impotent for grasping, and too 

 restricted in its energies for investigating, the multifarious 

 issues which the discussion of such a thesis would involve. 

 As coming events, however, are said by the poet to cast their 

 shadows before, so, as heralds and harbingers of truths be- 

 yond logical proof, come beliefs, faiths, even moral convic- 

 tions. Of this sort is the assurance of the balance established 

 by Nature at each passing epoch of existence in the world. 



The naturalist is impressed with the firm belief that the 

 number of animal species existing on the earth, and the 

 number of individuals in each species, are balanced and ap- 

 portioned in some way and by some mysterious co-relation to 

 the needs of the universe. 



Some presumptive testimony in favour of this belief is 

 afforded by the discussion, barely yet concluded, relative to 

 the effect of small-bird destruction. Without any more ela- 

 borate reasoning on this topic than follows necessarily as the 

 result of newspaper reading, the general concession will be 

 made by any one of unbiassed mind, that if small-bird destruc- 

 tion could be enacted to its exhaustive finality if every 

 small bird could be destroyed the aggregate of life thus 

 disposed of would be balanced through the increase of other 

 organisms. Insect life would teem and multiply to an extent 

 proportionate with the removal of an anterior restraining 

 cause. 



The nature of the topic on which we are engaged does 

 not force upon us the question, whether such proportionate 

 increase of insect life be advantageous or disadvantageous. 

 "What we are alone concerned to place in evidence is, the 

 balance kept up between vital organisms of different species 

 by Nature. Nor is the balance of vitality established between 

 different animal species. It also may be traced, and even 



