IRRITABILITY 43 



ing it up neatly inside after the fashion 

 of the ameba. When the sealing wax is 

 all digested the glass skeleton is extruded. 

 The whole process depends upon the 

 familiar forces which act at the surface 

 of all liquids. 



Such an experiment suffices to show 

 that we need not despair of finding me- 

 chanical explanations for reactions which 

 seem very complex and highly advanta- 

 geous. In reality we have succeeded in 

 finding such explanations so often that 

 many biologists feel that there is no logi- 

 cal necessity for regarding the simplest 

 cases of irritability as essentially differ- 

 ent from certain reactions found in non- 

 living systems. 



Other thinkers have a different atti- 

 tude. The power of the organism to 

 make continual adjustment between in- 

 ternal and external relations, and the co- 

 operation of its various parts, which we 

 call organization, seem to them beyond 

 our present powers of analysis. Not ig- 

 noramus but ignorahimus expresses their 



