BEHAVIOR AND BODY TEMPERATURE 85 



tool for making adaptive responses, there are activities 

 which are largely or wholly controlled by rather primi- 

 tive nerve nets or by glandular secretions and other 

 chemical substances. 



The activities of poikilotherms, and of a few homoio- 

 therms, are limited by temperature and other factors 

 in the environment and they may therefore be restricted 

 to particular times of day or to particular seasons of 

 the year. A hibernating animal is not wholly inactive. 

 Certain of its physiological processes continue at a slow 

 rate, but its behavioristic responses are absent. A poi- 

 kilotherm therefore is not able to have continuous rela- 

 tions with environment by receiving sensory stimuli and 

 responding in a more or less adaptive way through the 

 activation of effectors. During enforced periods of 

 quiescence it has a chance to forget lessons learned dur- 

 ing previous experiences in its environment. Homoio- 

 therms, with their separate pulmonary and systemic cir- 

 culations and effective mechanisms for temperature regu- 

 lation, permit their nervous systems to continue to func- 

 tion from day to day at a high level of activity. A 

 homoiotherm, except for short periods of rest from fa- 

 tigue, lives a continuously active life. 



In general metabolism increases in rate with in- 

 creased temperature, but every animal has an optimum 

 range where it is most active and efficient and above 

 which its activities may be abnormal. For example, an 

 amoeba shows its maximum rate of locomotion at 21.5 

 deg. C. and above or below that temperature moves more 

 slowly (Schwitalla, 1925). Ants crawl faster at higher 

 temperatures (Andrews, 1927). Some animals are ad- 

 justed to high temperatures and some to low. In ther- 

 mally stratified lakes and oceans particular species of 

 fishes and plankton organisms are found regularly to 



