THE IMPORTANCE OF SOCIAL LIFE 73 



pendently, feeding on bacteria and decaying vegetable mat- 

 ter. They reproduce by fission and in great numbers. This 

 goes on over a period of time; and then suddenly the indi- 

 vidual amoebae stop all independent activity and begin 

 streaming in toward centers, each center drawing toward it- 

 self thousands of individuals. The single cells do not fuse 

 but assemble and then move as one through the water with 

 perfect unison. The collective colonies settle finally in a fa- 

 vorable spot, and then a highly organized, cooperative ac- 

 tivity begins to elevate reproductive spores into the wind. 

 Some of the amoebae seem to be designated as stalk cells, and 

 they take their places by piling up on top of each other. 

 When the stalk is complete, others stream up to form a 

 spore mass which drys and is blown to new breeding waters, 

 where the cycle is repeated. 



Interesting instances at all levels in evolution, from the 

 smallest to the largest animals, are reported in the literature. 

 Carl E. Akeley tells of elephants in Africa stopping to help 

 a wounded comrade by lifting him with their tusks and 

 trunks, and of threatened herds gathering in a ring with the 

 larger beasts forming the outer circle. In social groups there 

 is, apparently, strength in numbers, and certainly better be- 

 havior is brought about by the companionship. T. H. Lang- 

 lois. Chief of the Ohio Bureau of Fish Propagation, reports 

 that he was able to cure the bass in the Bureau's ponds of 

 cannibalism by a change in the habitat. If the bass were placed 

 in weedy ponds, they were partially separated from each 

 other and tended to hide out in secluded spots, killing any 

 unlucky intruders. The pond population took on a gangster- 

 like psychology, and even plenty of food in all parts of the 

 pond did not stop the cannibalism. However, if the weeds 

 were cleared out, the fish were able to mingle freely, and, 

 food being adequate, they swam together and ate together, 

 but not each other. 



The relation of parent and offspring in developing tradi- 

 tions that culminated in human society and the human mind 



