Herrick, Physiological Problems. 367 



similarity in divergence as in the case of chords or octaves in 

 music. 



According to the geometrical theories prevailing, which state 

 that the specific peculiarities of idioplasm result from the arrange- 

 ment and structure of the micellae composing it, the influence upon 

 heredity w^ould sfeem to be proportional to the amount of idioplasm 

 present. This, however, it is not necessary to assume upon a 

 dynamic hypothesis. Any portion of an equilibrated system when 

 disturbed will tend to restore the entire trajectory. Especially will 

 this be true if a relation of rhythmical or cyclical motion is involved. 

 No theory of vital activity is complete which fails to take into 

 account the power of a cutting to produce a complete plant or of a 

 medusa to restore mutilations. The nisus for?nativiis or Bildungs- 

 kraft is, after all, only a necessity imposed on the mutilated tra- 

 jectory to complete itself and is lodged in no organ to the exclusion 

 of all others. It is more conspicuous and effective in the germ 

 than elsewhere. The complete separation of germplasm and 

 somatoplasm does not hold as to the possibility of reproduction, 

 and the new plant produced by graft or cutting inherits the type 

 more fully than the seedling in which the function of variation is 

 provided for according to Mendel's law. It is observed that 

 cells budding from vegetative parts when compared in their develop- 

 ment with the germinal individuals overleap the earlier stages in 

 development and this is what might be expected in the case of 

 organic activities already passed the earlier stages of complexity. 



The dynamic point of view serves clearly to throw into relief 

 the relation between diff'erent factors of evolution and develop- 

 ment. As C. M. Child well says in the closing paragraphs of 

 his Studies in Regulation:^ " The relation between form and her- 

 edity has never been satisfactorily determined. With the advance 

 of our knowledge the fact becomes more and more evident that the 

 organism is not merely a complex of structural elements ready 

 made by heredity for certain physiological activities, but rather 

 a complex of activities, in consequence of which morphological 

 structure develops." Dr. Child insists on the dift'erence between 

 physical and chemical structure of protoplasm and morphological 

 structure, the former representing capacity for activity or func- 

 tional activity in the broadest sense. According to this view, it is 

 functional capacity that is inherited rather than form. "Heredity 



^Journ. Exp. ZooL, VoL I, No. i. 



