ADOLESCENCE 215 



it needs it much, if it is to survive well or survive at all. On 

 the other hand, the criticism, whether of circumstances 

 or of society, does not always make for progress, and many 

 fine buds are probably killed or spoilt. While it may be 

 impossible to lay down general rules for human adolescents, 

 the important thing is that we realise clearly what is happen- 

 ing. And since freshness is rare and monotony common, 

 it seems a wise rule that our judgments should lean to 

 mercy's side. Running the gauntlet may be necessary, 

 but let us be sparing with those heavy-handed snubs 

 which are so fatal to the growth of the saving grace of 

 originality. 



In the fourth place, we may profitably link together the 

 two concepts of adolescence and plasticity. We have seen 

 that one of the biological certainties in regard to young 

 creatures is their plasticity in receiving modifications from 

 their surroundings. By modifications, as explained, we mean 

 changes due to peculiarities of nurture changes neither 

 inherited nor transmissible, so far as we know. Now, great 

 modifiability, as seen in caterpillars and tadpoles, for 

 instance, is characteristic of youth, and it is often during 

 the adolescent period that decision is given whether a piece 

 of juvenile veneer is to persist or not. Undesirable youthful 

 veneer is often slipped off; effective veneer is often con- 

 firmed. When youthful modifications, for good or ill, 

 survive the adolescent period, the chances are that they 

 will persist throughout life. 



In the fifth place, much of the biological importance of 

 adolescence is bound up with the central fact that it is the 

 period in which the promptings of sex-impulses first make 

 themselves normally assertive. In various ways for in- 

 stance, by the liberation of chemical excitants (or hormones), 

 which saturate through and through the body the sex- 

 impulses influence the whole being, transforming it not 



