REGENERATION AS FUNCTIONAL ADJUSTMENT 



S. J. HOLMES 

 With One Figure 



In a previous paper^ I have ventured to outline a general theory 

 of form regulation, based on the conception of an essentially 

 symbiotic relation between the parts of an organism. The con- 

 ception is, of course, nothing new, but, so far as I am aware, no 

 one has hitherto attempted to deduce from it a theory of regener- 

 ation and other processes of a regulatory nature. The theory 

 may be stated in brief as follows: The various parts of an 

 organism are supposed to stand in such a relation to each other 

 that each part derives some advantage or is helped to perform 

 its normal functions through the materials and stimuli it receives 

 from other and especially the contiguous parts of the organism. 

 Each part in turn contributes something to the normal functioning 

 of the parts surrouningit;the relation is one of mutual dependence. 

 Being mutually dependent, the parts of an organism tend to settle 

 into a condition of functional equilibrium. When a part of the 

 organism is removed and tissue of an undifferentiated nature is 

 produced in its place, this new tissue develops in the direction of 

 the missing part because this line of development is favored 

 through the influence of the surrounding parts. Whatever advan- 

 tages accrued to the part formerly in this position from its relations 

 to the parts around it would also accrue to this tissue in so far as 

 it diff^erentiates in the same way as the part removed. The new 

 tissue difi^erentiates according to the functional demands upon it 

 and its line of specialization may be regarded as a case of func- 

 tional hypertrophy. Regeneration of the missing parts, therefore, 

 may be interpreted as an expression and act of getting back into a 

 condition of functional balance. 



' Archiv fiir Entwickelungsmechanick, xvii, Bd., p. 265, 1904. 

 The Jourmal of Experimental Zoology, vol. iv, no. 3. 



