ON THE NATURE AND BASIS OF HEREDITY. 179 



As the organic world must, from the standpoint of evohition, be regarded as a 

 product of the physical world, we have always to take the physical aspects as our 

 point of departure. Our theoretical myths are largely due to reversing this natural 

 mode of procedure, not meaning to imply that from the physical side we always 

 come face to face with facts. Newton's emission or corpuscular theory, according to 

 which light consists of ])articles emitted from the luminous body, was just as much 

 a myth as the theory of transmission of hereditary qualities. The emission concep- 

 tion proved to be untenable and had to give way to a totally different view, accord- 

 ing to which Ught is not something transported from the sun, but a peculiar self- 

 propagating motion of the ether. 



Now, the ether set in vibration at the sun does not of course come to us, neither 

 does the initial vibration ever reach us. A ripple may appear to run over the surface 

 of water, but the appearance is illusive. The ripple is a new ripple at every instant, 

 and its seemingly running crest does not advance at all. So with the vibrations of 

 the ether. Successive particles vibrate in linear sequence, because they are identical 

 in nature and respond alike to the same condition. So also is it with hereditary 

 phenomena. Germ-cells behave alike in development, not because anything is 

 transmitted to them, but because they represent identical material and constitution, 

 and are exposed to essentially like environmental conditions. 



The development of the germ is said to end in the specific form characteristic 

 of the race. It is well to remember that we have in every development a flowing 

 sequence of specific forms, for every stage is as specific as the end-stage. In this 

 progressive change of form we see an interesting difference between the development 

 of the organism and the development of the crystal; nevertheless, the form is as 

 certainly a physical determination in the one as in the other. The crystal has its 

 specific form and sometimes several specific forms. In every case it owes the form 

 to the nature of its material elements and the conditions under which it arises. We 

 would not think of ascribing its form and symmetry to hereditary transmission; 

 neither would we think of intercalating directing or formative agents, distinct 

 from the material elements composing it. 



Fundamentally considered, the organism and the crystal are equallj^ "self- 

 determining" at every step, equally the products of intrinsic physical properties and 

 conditions. The crystal is said to grow by "accretion," the organism by "intus- 

 susception." But this is merely a superficial difference that does not affect the 

 general standpoint. From a physical standpoint the essential thing is not where 

 the elemental particles attach themselves, whether interstitially or superficially, 

 but that they attach theinselves in a self-regulating, determinate way, so that the typical 

 form at every step is, to use Jensen's terms, autogenic rather than allogenic. In 

 other words, the form is a "direct causal result," rather than an indirect one imposed 

 by special mediative factors, such as pangens, determinants, and the like. 



According to the view sketched, we see that recapitidation in the organic world 

 is a universal phenomenon as fundamental as in the crystal world. It is no hallu- 

 cination, but the great fact underlying every form of heredity, eveiy form of 

 development, every form of evolution. 



Ontogeny is recapitulation from top to bottom. Think how full of significance 

 is the recurrence of the cell-stage as the universal primordium in both plant and 

 animal development. And yet no two species start with germ-cells that could be 



