52 



THE SOCIAL LIFE OF ANIMALS 



plications, that freshness lies. Without for one min- 

 ute forgetting or minimizing the importance of the 

 right-hand limb of the last curve, it is for the more 

 romantic left-hand slope that I ask your attention. 



Fig. 2. A. Under some conditions the rate of bio- 

 logical action which is being measured is greatest with 

 the smallest population, and decreases as the numbers 

 increase. B. Under other conditions there is a distinct 

 decrease in the rate of the measured biological reaction 

 with undercrowding (to the left) as well as overcrowding 

 (to the right). 



Perhaps the simplest and most direct demonstra- 

 tion of certain harmful effects of undercrowding 

 comes from an experiment which I understand is 

 carried on spontaneously among undergraduate men 

 at certain universities and colleges of which X, or 

 perhaps better, Y, is an example. A certain number 

 of men gather together in a limited space under arti- 

 ficial light and undertake to consume a more or less 

 limited amount of stronger or weaker alcohol. If 



