Bionomics. 195 



plants or Liindstrom on the little shelters (domatia) 

 which various trees offer to useful mites, we gain the 

 impression that even the general life of plants is not 

 very different after all from that of animals. This, as 

 it seems to us, is the greatest result of the modern study 

 of the bionomics of plants. 



Although the idea of a struggle for existence is very 

 ancient, expressed, for instance, by Empedocles, Aris- 

 totle, and Lucretius, it remained little more The struggle 

 than a general impression until Darwin and for Existence * 

 Wallace showed not only its reality, but how it may 

 operate as a factor in evolution. Both of these natu- 

 ralists have referred to the work of Malthus as one of 

 the sources of their inspiration, and it has been pointed 

 out by Prof. Geddes that the biological emphasis on 

 struggle is entirely congruent with the keen competitive 

 conditions of an industrial age. 



The colour of Darwin's picture of nature certainly 

 suggests a very keen and continuous struggle for exis- 

 tence. He speaks of "the battle for life" and "the 

 severe, often recurrent struggle". "In a state of 

 nature, animals and plants have to struggle from the 

 hour of their birth to that of their death for existence." 

 On the other hand, it should be carefully observed that 

 Darwin used many saving-clauses. Thus, in speaking 

 of the struggle for existence, he says, "I should premise 

 that I use this term in a large and metaphorical 

 sense, including dependence of one being on another, 

 and including (which is more important) not only the 

 life of the individual, but success in leaving progeny ". 

 Similarly Mr. Wallace says, "The struggle for exis- 

 tence, under which plants and animals have been de- 

 veloped, is intermittent and exceedingly irregular in its 

 incidence and severity ". 



The reality of the struggle is beyond all doubt, but 

 there remains a lack of statistics and analysis with- 

 out which even the biologist can hardly escape from 

 platitudes. We require to have some measure of the 

 intensity of the struggle in actual cases, and a more 

 careful distinction between its different modes. It is 

 obviously unsatisfactory that the important generaliza- 



