Roux's Self Regulating Mechanism 95 



primitive slate. Thus it is that a wound or a fracture 

 is never so detrimental to the child as to the adult; but 

 it is also tnu- that with the same intensity and duration 

 of the educative influence directed toward the modifica- 

 tion of inborn tendencies the results are more permanent 

 the older the child is. 



This elasticity of development is proved by Roux 

 with his customary care in the following way. 



In one of his experiments on the effects of passive 

 deformations in the first stages of development he suc- 

 ceeded in bending a few frogs* embryos within their 

 gelatin envelopes by squeezing them between needles. "If 

 the needles were removed immediately after the deforma- 

 tion, the embryo at once took on again its previous form; 

 if they remained however a few hours the deformation 

 tended to be a persistent one and disappeared again 

 only in the course of several hours; a proof that an inter- 

 nal adaptation to the new form had already commenced, 

 but which was in its turn caused to disappear in the 

 course of further development, perhaps by the action of 

 growth forces inhibited during the deformation but re- 

 sumed upon the restoration of the normal form." 02 



Roux gives this dynamic elasticity of development 

 tin- name "mechanism of self regulation." Let us note 

 again that the absence of this elasticity in adult organisms, 

 which remain plastic in relation to the somewhat persist- 

 ent, deforming influences of the environment, would de- 

 note that this mechanism is active only during embryonic 

 life. Now the continued action exercised by the central 

 zone of development constitutes precisely such a mechan- 



"Wilhelm Roux: Zur Orientierung iiber einige Probleme dcr 

 embryonalen Kntwicklung. Zeitschr. f. Biol. Bd. XXI. Miinchen, 

 July 1885. P, 515516. Gesamm. Abhandl. Zw. Bd. P. 245. 



