240 THE HAUNTS OF LIFE 



It has its drawbacks, this instinctive capacity, 

 but it makes for success as long as the unex- 

 pected does not happen. 



The fourth reason for the surpassing success 

 of insects in the system of animate nature is 

 to be found in their variability or plasticity, 

 linked with that of the plant world. While 

 the fundamentals of an insect's body are al- 

 ways the same, the details vary without end, 

 and this has enabled insects to find an unusual 

 number of niches of opportunity, especially 

 in their vital linkages with the likewise very 

 variable, flowering plants. Now, the more 

 niches of opportunity a class of animals can 

 find, the greater will be its success. 



A Russian naturalist, Chetverikov, has 

 called attention to a fifth reason for the suc- 

 cess of insects. It concerns their skeleton. In 

 backboned animals the skeleton of living 

 gristle or bone is inside the body; in insects 

 and other jointed-footed (Arthropod) animals 

 the skeleton of not-living chitin is outside 

 the body. Now it is argued that this entirely 

 different kind of body architecture made it 

 possible for insects to become very minute 

 without ceasing to be very effective. It was 

 more practicable to become small when the 



