9^ THE SOCIAL LIFE OF ANIMALS 



verified by careful laboratory experiments. A more 

 crucial test involves individuals of the same species: 

 all snails, let us say, or all goldfish. Is there some 

 optimum size of the population at which individuals 

 grow most rapidly? 



For years I have been studying different aspects of 

 this problem with the aid of a succession of com- 

 petent, critical research assistants and associates. The 

 names of these young scientists are interesting and, 

 I think, important. They include Drs. Bowen, Welty, 

 Shaw, Oesting and Evans, and Messrs. Livengood, 

 Hoskins, and Finkel, all of whom have independ- 

 ently obtained the basic results I am about to de- 

 scribe. (13, 14, 76) 



We have used goldfish for our experimental ani- 

 mals, because these are inexpensive, easy to obtain, 

 hardy under laboratory conditions, and able to stand 

 daily handling. 



In order to have a consistently constant water we 

 make up a synthetic pond water by dissolving in good 

 distilled water salts of high chemical purity. Into 

 such water goldfish about three inches long are 

 placed in sufficient number so that they will give a 

 conditioning coefficient of about twenty-five. Let me 

 explain: this coefficient is obtained by multiplying 

 the number of fish by their average length in milli- 

 meters and dividing by the number of liters of water 



