194 EVOLUTION 



surroundings the living creature is able to 

 adjust itself temporarily. The warm-blooded 

 bird or mammal can within limits adjust its 

 heat-production and heat-loss so that the 

 temperature of the body remains the same 

 whether that of the environment rises or 

 falls. In the case of many of these transient 

 adjustments there remains no abiding result 

 that can be detected. 



(4) Insensibly, however for it is all a 

 matter of degree we pass to cases where 

 the responses to environmental change last 

 for a considerable time. Sun-burning on a 

 summer holiday, increase in the size of a 

 muscle after a course of exercises, the 

 blanching of the banked-up celery are familiar 

 illustrations. The bodily change has taken 

 a firmer hold than in the case of transient 

 adjustments, but it is still a passing change. 

 Like a bow unstrung the organism rebounds, 

 approximately to its previous state. 



Semon has recently propounded a theory 

 of the "IVfrW 1 ? 1 ?" which is of interest in 

 this connection. The general idea of it is, 

 that when living matter is affected hv a 

 s ualit canne h 



* ti Wfl ! .fo fifo**** t.h fi stimulus . Even a bar of 



iron is not quite the same after it has been 



. once struck; how much more a living crea- 



\ ture which is specialized towards gaining and 



