THE PROBLEMS OP PHYSIOLOGY. 243 



more conspicuous and important differentiations of functions 

 have arisen, it is as much as can be expected. 



267. It will be best, for brevity and clearness, to deal 

 with these physiological problems as we dealt with the 

 morphological ones to carry on the inductive statement and 

 the deductive interpretation hand-in-hand: so disposing of 

 each general truth before passing to the next. Treating 

 separately vegetal organisms and animal organisms, we will 

 in each kingdom consider: first, the physiological differen- 

 tiations and accompanying changes of structure which arise 

 between outer tissues and inner tissues; next, those which 

 arise between different parts of the outer tissues ; and, finally, 

 those which arise between different parts of the inner tissues. 

 What little has to be said concerning physiological integra- 

 tion must come last. For though, in tracing up Morpho- 

 logical Evolution, we have to study those processes of inte- 

 gration by which organic aggregates are formed, before 

 studying the differentiations that arise among their parts; 

 we must, contrariwise, in tracing up Physiological Evolution, 

 study the genesis of the different functions before we study 

 the interdependence that eventually arises among them and 

 constitutes physiological unity. 



