No. 627] 



ADAPTATION 



341 



havior of a Paramecium? Each is the extension of an 

 article of philosophic faith far beyond the realm of ex- 

 perience. But this is no essential part of our present 

 argument. Let us consider whether the trial and error 

 principle may not be applicable to other phenomena than 

 the bodily movements of animals. 

 Jennings asks: 



Is it possible that interference ^vith the i)hysi()l()sieal processes may 



condition just sketched, unlimited possibilities for the selection of dif- 

 ferent chemical processes. The body is a great mass of the most varied 



direction, all those indeed that are possible— are occurrinp: at all 



Looking for evidence that such a process of selection 

 does actually occur in physiological regulation, Jennings 

 cites the experiments of Pawlow, in which tlie latter 

 habituated dogs to various kinds of foods and noted tlie 

 effects upon the diuvsti\c Juicos. In llicsc cNpci-iniciits 

 the adaptive changes in \hv :u-iivitir< of ilic ,li-r.iiv(. ul;ui<U. liiiino- the 

 digestive juices to the ton,l i;ikfn, ,ln nm .H-,-uf ;ii mir,- niid .•.miplctely 



Jennings concedes : 



