AGGREGATIONS OF HIGHER ANIMALS IO5 



and Dr. Thomas Park looked into the matter inde- 

 pendently. (88) He found the situation very much 

 as it had originally appeared to be. A Scotsman 

 named Maclagen had a curiosity along the same line 



2 4 8 16 32 64 



/nitiaC population per ^2 Sms, of f/oar 



Fig. 17. Flour beetles reproduce more rapidly if more 

 than one pair is present. 



and independently re-checked the whole matter with 

 the same results. (77) Three separate workers in 

 three different laboratories have now obtained essen- 

 tially similar results with these same beetles, and the 

 chances that all are mistaken are rather remote. 



One of them, Dr. Thomas Park, has proceeded to 

 analyze the factors involved. (89) He finds that the 

 results come from the interaction of two opposing 

 tendencies. In the first place, adult beetles roam at 



