114 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



restitutions that is, all restorations not beginning at the 

 wound itself the theory that the removing of obstacles 

 is the stimulus to restoration becomes, as we have said, 

 quite impossible. 1 



But where then is the stimulus to be found ? There 

 is another rather simple theory of the " Auslosung " of 

 restitutions, 2 which starts from the phenomena of com- 

 pensatory hypertrophy and some occurrences among plants. 

 The removal of some parts of the organism, it is said, 

 will bring its other parts into better conditions of nutrition, 

 and therefore these parts, particularly if they are of the 

 same kind, will become larger. Granted for the moment 

 that such a view may hold in cases when one of a pair 

 of glands becomes larger after the other has been removed, 

 or when pruning of almost all the leaves of a tree leads to 

 the rest becoming larger, it certainly must fail to explain 

 the fact that in other cases true new formations may arise 

 in order to restore a damaged part, or that the latter may 

 be regenerated in its proper way. For merely quantitative 

 differences in the mixture of the blood or of the nourishing 

 sap in plants can never be a sufficient reason for the highly 

 typical and qualitative structure of newly -formed restitutions. 

 And even in the most simple cases of a mere increase in 

 the size of some parts, that is, in the simplest cases of 

 so-called compensatory hypertrophy, 3 it is at least doubtful, 



1 T. H. Morgan is very right in stating that, in regeneration, the 

 " obstacle " itself is newly formed by the mere process of healing, previous 

 to all restitution, and that true restitution happens all the same. 



2 I merely mention here the still "simpler" one applicable of course 

 to regeneration proper exclusively that for the simple reason of being 

 "wounded," i.e. being a surface open to the medium, the "wound" brings 

 forth all that is necessary to complete the organism. 



3 That compensatory hypertrophy cannot be due to "functional adapta- 

 tion " to be analysed later on was proved by an experiment of Ribbert's. 



