BEHAVIOR AND BODY TEMPERATURE 87 



check overheating can live a continuously active life vnth 

 its body at the optimum temperature for metabolism. 

 When the environment varies it may experience sensa- 

 tions of pain or discomfort to a greater degree than is 

 possible among poikilotherms, but such suffering is the 

 penalty for living continuously with full perception of 

 stimuli. It is perhaps more than compensated for by the 

 opportunity for mental development that continual living 

 gives. Because they are able to live continually at an 

 optimum rate birds and mammals are quicker, better 

 coordinated, and more astute than reptiles, amphibians, 

 or fishes. 



A poikilotherm must seek an environment where a 

 constant temperature obtains or confine its activities to 

 favorable times. A constant environment is the ideal. 

 A homoio therm can not only remain active at all times 

 but is able also to enjoy the intellectual luxury of seeking 

 thermal variation in its environment. It thus gains a 

 greater variety of experiences and these react to produce 

 a more experienced and a more capable controlling nerv- 

 ous mechanism. The behavior of a homoiotherm there- 

 fore proceeds on a higher level than that of a sloAvly- 

 responding, fitfully-living poikilotherm. 



A few colonial insects have attained to the advantages 

 which go with continuous living at temperatures approach- 

 ing their optima. Honey bees gather in a close cluster, 

 within a hive or hollow tree where they are protected 

 somewhat from cold by wood insulation and there main- 

 tain a comparatively high temperature by metabolic ac- 

 tivity. When their nest cavity cools, they beat their 

 wings and raise the temperature, largely through muscu- 

 lar activity. The temperature of a cluster inside a hive 

 may remain as high as 20 to 30 deg. C, while the tem- 

 peratures outside are varying between 9 and 11 deg. C. 



