26 ANIMAL LIFE AND SOCIAL GROWTH 



Insects also may or may not recognize the exist- 

 ence of these strata. Even in one group, the 

 termites, there are forms that are Hmited to one 

 level and others that burrow in the ground and 

 range to the tree-tops. Here as in all phases of 

 human and non-human sociology the general 

 principles stand out plainly, but there are many 

 exceptions. 



Within one and the same stratum, animals 

 recognize different sorts of regions as making dis- 

 tinct habitats. In the tropical rain-forest again, 

 one of the most obvious distinctions in the dry 

 season is the nearness to water. Land isopods, 

 land crabs, the long-legged spiders known as 

 harvestmen, frogs and toads, crocodiles, some 

 lizards and turtles, to mention no more, are lim- 

 ited to the moister regions, while others, equally 

 representative, are found generally or exclusively 

 on dryer ground. 



But not all moist or dry regions of the forest 

 floor have a similar set of animal inhabitants. 

 The animals themselves distinguish between 

 different sorts of soil or between different plants 

 that in turn are limited by the soil conditions. 

 In Panama during the dry season, it is useless to 

 try to collect Peripatus regardless of soil or mois- 

 ture conditions, unless in the immediate vicinity 

 of a decaying log or stump which is well along its 

 way back to humus. 



