ORGANIC EVOLUTION — THE FACTORS 63 



" That other kind of repair which shows itself in the 

 regeneration of lost members, is comprehensible only as 

 an effect of actions like those refen-ed to. The ability 

 of an organism to recomplete itself when one of its 

 parts has been cut off, is of the same order as the 

 ability of an injured crystal to recomplete itself. In 

 either case, the newly-assimilated matter is so deposited 

 as to restore the original outline. And if, in the case 

 of the crystal, we say that the whole aggregate exerts 

 over its parts a force which constrains the newly-inte- 

 grated atoms to take a certain definite form, we must 

 in the case of the organism assume an analogous force." 

 —lUd. vol. i. PI). 178-9. 



"... We must infer that a plant or animal of any 

 species is made up of special units, in all of Avhich 

 there dwells the intrinsic aptitudes to aggregate into 

 the form of that species; just as in the atoms of a salt 

 there dwells the intrinsic aptitude to crystallize in a 

 particular way." — Ihid. p. 181. 



"Setting but with these physiological units, the 

 existence of which various organic phenomena compel 

 us to recognize, and tlie production of which the general 

 law of Evolution thus leads us to anticipate ; Ave get an 

 insight into the phenomena of Genesis, Heredity, and 

 Variation. If each organism is built of certain of these 

 highly-plastic units peculiar to its species — units which 

 slowly work towards an equilibrium of their complex 

 polarities, in producing an aggregate of the specific 

 structure, and which are at the same time slowly 

 modifiable by the reaction of this aggregate — we see 

 why the multiplication of organisms proceeds in the 

 several Avays, and Avith tlie various results, Avhich 

 naturalists have observed. 



" Heredity, as shoAvn not only in the repetition of the 

 specific structure, but in the repetition of ancestral 

 deviation from it, becomes a matter of course ; and it 

 falls into unison Avith the fact that, in various simple 

 organisms, lost parts can be replaced, and that, in still 

 simpler organisms, a fragment can develop into a 

 whole."— ///iW. pp. 287-8. 



