124 THE BEGINNINGS OF II FE. 



be by the great quantity of their contained motion, they 

 exhibit in an extreme degree the secondary redistribu- 

 tions which contained motion facilitates. The history 

 of every plant and every animal, while it is a history 

 of increasing bulk, is also a history of simultaneously- 

 increasing differences among the parts. This trans- 

 formation has several aspects. . . . The chemical 

 composition which is almost uniform throughout the 

 substance of a germ^ vegetal or animal, gradually 

 ceases to be uniform. . . . Simultaneously there arise 

 contrasts of minute structured' These contrasts gra- 



^ Loc. cit., p. 334. But these gradually increasing complexities of 

 structure which are observable in the development of living matter, are 

 only very typical instances of changes vi^hich perpetually tend to occur — 

 although less obviously — in all other forms of matter. Masses of similar 

 units, constantly acted upon by intrinsic and extrinsic forces, ever tend 

 to become heterogeneous. Homogeneity, as Mr. Spencer has so fully 

 explained, is a condition of unstable equilibrium. He says (loc. cit., 

 p. 429) : — ' But all finite forms of the homogeneous — all forms of it 

 which we can know or conceive, must inevitably lapse into heteroge- 

 neity. In three several ways does the persistence of force necessitate 

 this. Setting external agencies aside, each unit of a homogeneous 

 whole must be differently affected from any of the rest by the aggregate 

 action of the rest upon it. The resultant forces exercised by the aggre- 

 gate on each unit, being in no two cases alike in both amount and 

 direction, and usually not in either, any incident force, even if uniform in 

 amount and direction, cannot produce like effects on the units. And 

 the various positions of the parts in relation to any incident force pre- 

 venting them from receiving it in uniform amounts and directions, a 

 further difference in the effects wrought on them is inevitably produced.' 

 A very interesting example of such a differentiation of a homogeneous 

 material may be seen by pouring a small quantity of varnish, composed 

 of shell-lac dissolved in naphtha, upon paper (loc. cit., p. 404) — though 

 the effects are here complicated by the rapid evaporation of the solvent. 



