ADAPTATION 179 



taken as embracing everything that is external to the 

 reacting cells. But of course also here the demonstration 

 of single formative agents does not detract in the least from 

 the adaptive character of the reaction itself. So we may 

 say, perhaps, that localised pressure is the formative stimulus 

 for the secretion of skeleton substance at a particular point 

 of the bone tissue, or of the fibres of the connective tissue ; 

 the merely quantitative adaptations of muscles might even 

 allow of a still more simple explanation. 1 But adaptations 

 remain adaptations in spite of that ; even if they only 

 deserve the name of " primary ' :> regulations. 



THEORETICAL CONCLUSIONS 



We have stated in the analytical introduction to this 

 chapter and elsewhere, that functional changes, which lead 

 to morphological adaptations of both of our groups, may 

 arise not only from changes of factors in the medium, but 

 also from a removal of parts. As such removal is generally 

 followed by restitution also, it is clear that restitutions and 

 adaptations very often may go hand in hand, as is most 

 strikingly shown in a fine series of experiments carried out 

 by Vochting, which we have already alluded to. Here again 

 I should like to lay the greatest stress upon the fact that, 

 in spite of such actual connections, restitutions and adapta- 

 tions always have been separated from another theoretically, 

 .and that the forms are never to be resolved into sums of 

 the latter. Such a view has been advocated by some recent 



1 Loeb has advocated the view that the ' ' adaptive " growth of working 

 muscles is simply due to the presence of a greater number of molecules in 

 their protoplasm, muscular activity being generated by a process of chemical 

 decomposition. 



