118 ANIMAL LIFE AND SOCIAL GROWTH 



though the group exercises some sort of soothing 

 effect upon the members that compose it. All 

 these records are for animals which are not gen- 

 erally regarded as being social. 



The case of the serpent starfishes is illuminating. 

 When similar lots of these marine animals are 

 placed so that half are grouped and the other half 

 are isolated, each individual being exposed to the 

 same quantity of water, the grouped animals use 

 less oxygen in the early stages of the experiment 

 than do the isolated ones. As time goes on and 

 the animals are kept without food, the isolated 

 animals come to have a higher rate of oxygen 

 consumption and finally mutilate themselves by 

 fragmenting their arms sooner than do the grouped 

 individuals. In the early stages of such an ex- 

 periment, the starfishes are using less oxygen if 

 grouped and in the later stages they use more. 

 The rate of oxygen consumption falls with the 

 process of starvation both for the isolated and the 

 grouped starfishes but more rapidly for the former 

 which first lose the ability to keep themselves 

 intact. After a period of starvation the grouped 

 starfishes are definitely in better condition than 

 if they were isolated. Such conditions hold when 

 the animals are not in the breeding season. Dur- 

 ing the time of breeding activities it is impossible 

 to predict the relations between oxygen consump- 



