120 SEX 



good illustration of the law of diminishing 

 return ; it is an ascent whose gradient be- 

 comes steeper and steeper towards the top. 

 But although the early rapidity of growth is 

 never afterwards approached, there is often 

 in animals, as in man, a remarkable re- 

 acceleration towards adolescence. This means 

 a serious drain on the available energies of 

 the organism, and the candle cannot be burnt 

 at both ends. There is increasing stability 

 and yet increasing instability, there is great 

 vigour and yet great " slackness," and the 

 rapidly growing adolescent is naturally a 

 good deal preoccupied organically, not con- 

 sciously, preoccupied with his or her internal 

 affairs. All this means that he or she should 

 have plenty of rest and plenty of play. 



The study of adolescent animals leads us 

 to include in our conception of adolescence 

 the idea of internal change, rearrangement, 

 and readjustment. The adolescent creature 

 becomes more complex, from its teeth to its 

 nerve-paths ; there is new differentiation. 

 But it also becomes if adolescence be suc- 

 cessful more controlled, more unified, more 

 strongly vertebrated, more toughly and subtly 

 knit together ; there is new integration. This 

 twofold progress is not achieved without cost; 

 there are " growing pains." In the tran- 

 sition from tadpole to frog, from caterpillar 

 to butterfly, there are remarkable processes of 

 breaking down and rebuilding, and crises of 

 inflammation that are sometimes fatal. Now 

 we must in some measure carry with us to 

 the study of human adolescence this idea of 

 redifferentiation and reintegration (i.e. of 



