253 



less highly organised than itself, and perhaps, from being possessed 

 of superior strength and faculties, or, from being in larger numbers, 

 exercising a wider influence on the sphere in which they move. 



Many of these have conflicting interests. The very existence of 

 some necessitates the death of others ; this one preying upon a 

 second, and this second upon a third, giving rise to varied modes of 

 attack and defence, and calling into play all those marvellous habits 

 and instincts by which they are severally enabled to hold their 

 place in the world, to sustain life and to continue their species. 



And life is a yet more complicated thing than this. Some 

 animals may prey on others, but a large number feed on vegetable 

 substances, which are therefore, directly or indirectly, the support of 

 all. And then have we to enter upon a new set of conditions 

 necessary to be fulfilled in order that plants as well as animals may 

 live, and grow, and propagate — conditions of soil, heat and moisture, 

 suited to as great a variety of forms of structure and organisation as 

 that which we find in the animal kingdom, yet liable to be disturbed, 

 or to fail altogether, from numberless accidents. Or if these con- 

 ditions continue unaltered, other accidents may prove equally fatal. 

 Plants as well as animals are at constant war with each other, the 

 stronger overpowering the weaker, and obliging them to give place ; 

 or, if they are the food of certain animals, to other animals they 

 may be indebted for their own existence, and if these animals are 

 destroyed the plants perish with them.* 



And how is our idea of life still further enlarged, when we 

 connect the different forms of life now moving around us with 



* Darwin has well illustrated tliis remarkable relationship between plants 

 and animals in the case of the heartsease and red clover, which are fertilised 

 by humble-bees. He says he has " very little doubt that if the whole genua 

 of humble-bees became extinct or very rare in England, the heartsease and 

 red clover would become very rare, or wholly disappear." He then goes on 

 to remark that " the number of humble-bees in any district depends in a great 

 degree on the number of field mice, which destroy their combs and nests ; and 

 the number of mice is largely dependent, as everyone knows, on the number 

 of cats. Hence it is quite credible that the presence of a feline animal in large 

 numbers in a district might determine, through the intervention first of mice 

 and then of bees, the frequency of certain flowers in that district I"— Origin of 

 Species, pp. 73, 74. 



