wider sense. Thus the formation or evolution of a race of animals involves a dissipation of motion, the tendency to irregular changes being resolved into systematic variation,-freedom to vary in any direction, merging gradually into the tendency to change only in specific directions and according to uniform law. So with other cases, even less like mere physical processes of aggregation, as we see in national, municipal, and social groupings. The law for each aggregate becomes more and more definite for each as time passes, precisely as the aggregates themselves become so.

We now come to statements belonging to the à priori aspect of the subject. It is evident that the only way in which we can conceive an utter absence of all tendency to the redistribution of matter and motion is by conceiving perfect uniformity throughout the entire universe: then and then only would all matter be related to all other matter in a manner absolutely indifferent, so that there would be no tendency either to aggregation or to any change in motions already existing, or to the state of absolute rest (if such were the condition of the primary and absolutely uniform universe thus conceived). Thus we have, next, the statements that

8. In the absence of a homogeneity that is infinite and absolute, the redistribution, of which evolution [formation of aggregates] is one phase, is inevitable. The causes which necessitate it are,—

9. The instability of the homogeneous, which is consequent upon the different exposures of the different parts of any limited aggregate to incident forces. The transformations hence resulting are complicated by,—

10. The multiplication of effects. Every mass and part of a mass on which a force falls, subdivides and differentiates that force, which thereupon proceeds to work a variety of changes; and each of these becomes the parent of similarly multiplying changes, the multiplication of them becoming greater in proportion as the aggregate becomes more heterogeneous.

It will be observed that Mr. Spencer, in statement 8, recognises that only infinite and absolute uniformity could produce absolute stability. It appears to me that the same condition is required in order that evolution should be simple. For wherever, in the neighbourhood of any forming mass, or at whatever distance from it, there is a want of uniformity, the circumstances are not such that simple evolution can result; and we can imagine no circumstances in which, however remote might be the region where absolute uniformity ceased, the effect of such homogeneity would not in the long run be felt, resulting in what Mr. Spencer has described as compound evolution.

In statement 9 Mr. Spencer points out that uniformity in itself is essentially unstable. That which is uniform in structure inevitably tends to become diverse in structure when it is exposed to diverse conditions. The slightest breath of air will ripple the surface of level water, while powerless to affect the onward course of a wave. It is so throughout nature. Opposing forces may result in a condition of stable equilibrium; absolutely uniform conditions are, of their very nature, unstable.

In like manner, statement 10 needs little explanation and no proof. It is evident that in every process of evolution the various forces which produce various effects must be infinitely varied in their operation, according to the condition of the various parts of the aggregating whole. With every variation of their effects, the condition of that aggregating whole varies further. The variations thus arising may be cumulative in some parts or self-correcting in others, whence come into existence regions of greater variety and regions tending to such uniformity as results from counterpoised variations. Thus the aggregate becomes more and more varied in detail as well as in general-these sub-regions, so to speak, of uniformity dividing off regions of diversity. We may again use as an illustration the effect of winds upon the sea. The surface which had been uniform becomes uneven under the diverse action of the wind on various parts. Afterwards the wind, as it falls on the waves which traverse the water's surface, is modified in direction by their resistance, and, being deflected in various ways, falls yet more diversely than before on the different parts of the water-surface: hence arises another kind of diversity, a minor order of varieties, which varieties in turn produce other and yet smaller forms of variety, -the number of changes thus resulting being continually greater and greater as the surface becomes more and more disturbed.

We might find illustrations of this law in the star depths, in the formation of a planetary system, in the shaping of such a world as our own earth. But we have illustrations more immediately interesting in relation to the general doctrine of evolution. What Darwin defines as the complex relations of animals and plants to each other in the struggle for existence affords an admirable illustration of the diversity of effects resulting from the inter-relation of varied action and varied condition in that which is acted upon. Consider, for instance, the following passage in the "Origin of Species ":" In several parts of the world insects determine the existence of cattle: perhaps Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they

swarm northward and southward in a feral state; and Azara and Reugger have shown that this is caused by the greater number in Paraguay of a certain fly, which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by other parasite insects. Hence, if certain insectivorous birds do decrease in Paraguay, the parasite insects would probably increase, and this would lessen the number of the navel-frequenting flies,-then the cattle and horses would become feral, and this would certainly greatly alter (as, indeed, I have observed in parts of South America) the vegetation; this again would largely affect the insects; and this, the insectivorous birds, and so onwards in ever-increasing circles of complexity. Not that under nature the relations will ever be as simple as this. Battle within battle must be continually recurring with varying success; and yet, in the long run, the forces are so nicely balanced that the face of nature remains for long periods of time uniform" [that is, with such uniformity as results from omnipresent variety], though assuredly "the merest trifle would give the victory to one organic being over another."

We are led directly to recognise among the causes of increasing variety

11. Segregation, which is a process tending ever to separate unlike units, and to bring together like units-so serving continually to sharpen, or make definite, differentiation otherwise caused.

As the result of these processes, a balancing of the forces at work arises from the matter worked on assuming those conditions which best favour their existence. The waves on our illustrative sea came to have just dimensions and just periods of oscillation on the greater scale, and they in turn are traversed by minor waves, and these by wavelets, and these in turn by ripples, harmonising with the winds and the variations of the winds which originally produced them. Thus, passing from the illustration to the processes of evolution illustrated—

12. Equilibration is the final result of these transformations which an evolving aggregate undergoes. The changes go on until there is reached an equilibrium between the forces which all parts of the aggregate are exposed to, and the forces these parts oppose to them. Equilibration may pass through a transition stage of balanced motions (as in a planetary system), or of balanced functions (as in a living body), on the way to ultimate equilibrium; but the state of rest in inorganic bodies, or death in organic bodies, is the necessary limit of the changes constituting evolution.

This tendency to uniformity, really arising as a result of the con

stant subdivision and multiplication of diversities, is seen on the largest scale (known to us) in the generally recognised tendency of this universe of ours to that condition of uniform temperature which would constitute its death, and on the smallest scale, in the natural death of animals and plants or of parts of these. Our sun is alive so long as, being of a higher temperature, he communicates heat to what lies around him; the stellar system is alive so long as some of its constituent parts are at higher levels of energy than the rest-just as a sea is active when the various parts of its surface are at different levels. The animal body is alive so long as the diverse energies of its various parts result in the processes of circulation and respiration. With uniformity resulting from the subdivision and distribution of energy comes death. But after death come processes akin to renewed life; though no longer the same life.

13. Dissolution is the counter-change which sooner or later every evolved aggregate undergoes. Remaining exposed to surrounding forces that are unequilibrated, each aggregate is ever liable to be dissipated by the increase, gradual or sudden, of its contained motion; and its dissipation, quickly undergone by bodies lately animate, and slowly undergone by inanimate masses, remains to be undergone at an indefinitely remote period by each planetary and stellar mass, which since an indefinitely distant period in the past has been slowly cooling; the cycle of its transformation being complete.

We can of course only infer from analogy that the heavenly bodies and systems of bodies after the equilibration of their energies with their surroundings,--after, for instance, each sun has exhausted its superior heat, and therefore no longer ceases to part with heat to surrounding matter,-will undergo a process of dissolution, thus com pleting the cycle of its transformations. It is so, we see, on the minor scale in every case with which we can deal. It is so with the individual members of animal and vegetable races, with families of animals and vegetables, with groups of these families, with nations, with social organisations. In every case we see how the life of each aggregate is limited in time, and tends to death, but how, also, after death the parts of the aggregate are dissolved, and become ready to take part in the formation of other aggregates. Hence

14. This rhythm of evolution and dissolution, completing itself during short periods in small aggregates, and in the vast aggregates distributed through space completing itself in periods which are immeasurable by human thought, is, so far as we can see, universal and eternal-each alternating phase of the process predominating now in this region of space and now in that, as local conditions determine.

From the cases considered in the last paragraph, we can proceed with a certain degree of confidence to cases more extended, until we recognise in the solar system (for instance) the evidence of youth, and life, and old age, as stages of evolution, though our processes and the range of our observation are too limited to enable us to judge (otherwise than from analogy) that after old age and death in these vast physical aggregations there comes a stage of dissolution completing the cycle of transformations. All we can say on that point is that, as in every case we can deal with to the end, we have found dissolution following the state of equilibrium which we call death in the case of the individual and compare to death in other cases, so also it is with those cases which (because of the limited range of our vision) we can only deal with in minute parts. We judge then that planets after this stage of death have a stage also of dissolution, though no physical experience enables us to say what that stage is like. We pass also to higher orders of being. We see suns of various ages throughout stellar space, and learn to recognise in their case also progression and evolution, up to and beyond the fulness and prime of stellar life. In their case also must come death, with equilibration between their energies and the receptive capacities of matter around them; and after this physical death must come, though in ways we cannot perceive, a process of dissolution completing the cycle of transformations. So also with higher orders, with systems of suns, with systems of such suns, and so on, absolutely without end.

We come then to the final statements respecting the operations of nature and their significance. After what has been already explained, these need no words of mine to make them clearer. Nor could this paper be better closed than in the very words of this great teacher of our age :—

15. All these phenomena, from their great features even to their minutest details, are necessary results of the persistence of force, under its forms of matter and motion. Given these as distributed through space, and their quantities being unchangeable either by increase or decrease, there inevitably result the continuous redistributions distin- . guishable as evolution and dissolution, as well as all those special traits above enumerated.

16. That which persists, unchanging in quantity, but ever changing in form, under these sensible appearances which the universe presents to us, transcends human knowledge and conception, IS AN UNKNOWN AND UNKNOWABLE POWER, WHICH WE ARE OBLIGED TO RECOGNISE AS WITHOUT LIMIT IN SPACE, AND WITHOUT BEGINNING OR END IN TIME. RICHARD A. PROCTOR.