HEREDITARY TRANSMISSION.

blooded ani

571 ed mammals. Perhaps those first arising might, like our hi- Cold and hot bernates, lead a sluggish existence, with imperfect respiration; mals. but, as the media improved and the temperature declined, more vigorous forms of life emerged, though we have probably to descend to the Tertiary epoch before we meet with birds, which of all animals have the most energetic respiration, and possess the highest heat.

of the sea.

As with the atmosphere, so with the sea. Variations in its composition must control the organisms it contains. With its saline The organisms constituents its life must change. Before the sunlight had removed from the atmosphere so much of its carbonic acid, decomposing it through the agency of plants, the weight of carbonate of lime held in solution by the highly carbonated water was far greater than was subsequently possible, and the occurrence of limestone became a necessary event. With such a disturbance in the composition of the sea-water, its inhabiting organisms were necessarily disturbed. And so again, subsequently, when the solar heat began to preponderate on the surface over the subsiding interior heat, the constitution of the sea-water, as respects its salinity, was altered through difference of evaporation in different latitudes, an effect inevitably making a profound impression on marine animal life.

itary transmis

Supported by the facts that have been mentioned respecting the later fossils of Australia and Brazil, and their analogy to forms Nature of herednow existing in those countries, much stress was laid on the sion. hereditary transmission of structure, and hence the inference was drawn that such examples are of a mixed nature, depending in part on external agency, in part on an interior developmental force. From marsupial animals, marsupials will issue; from placental ones, those that are placental. But here, perhaps, an illustration drawn from the inorganic kingdom may not be without interest and use. Two pieces of carbonate of lime may be rolling among the pebbles at the bottom of a brook, one perpetually splitting into rhomboids, the other into arragonitic prisms. The fragments differ from one another not only thus in their crystalline form, but in their physical qualities, as density and hardness, and in their optical qualities also. We might say that the calc-spar crystals gave birth to calc-spar crystals, and the arragonitic to arragonite; we might admit that there is an interior propensity, an intrinsic tendency to produce that result, just as we say that there is a tendency in the marsupial to engender a marsupial; but if, in our illustration, we look for the cause of that cause, we find it in a physical impression lọng antecedently made, that the carbonate of lime, crystallizing at 212° Fahr., produces arragonite, and, at a lower temperature, calc-spar; and that the physical impression thus accomplished, though it may have been thousands of years ago, was never cast off, but perpetually manifested itself in all the future history of the two samples. That which we

sometimes speak of as hereditary transmission, and refer to an interior property, peculiarity, or force, may be nothing more than the manifestation of a physical impression long antecedently made.

In the last place, the idea of an intrinsic force of development is in connection with time and a progression, and only comes into prominence when we examine a limited portion or number of the things under consideration. The earth, though very beautiful, is very far from being The broken or- perfect. The plants and animals we see are only the wrecks ganic chain. of a broken series, an incomplete, and, therefore, unworthy testimonial of the Almighty power. We should judge very inadequately of some great author if only here and there a fragmentary paragraph of his work remained; and so, in the book of organization, we must combine what is left with what we can recover from past ages and buried strata before we can rise to a comprehension of the grand argument, and intelligibly grasp the whole work.

age of the

Of that book it is immaterial to what page we turn. It tells us of efEnormous fects of such magnitude as imply prodigiously long periods of earth. time for their accomplishment. Its moments look to us as if they were eternities. What shall we say when we read in it that there are fossiliferous rocks which have been slowly raised ten thousand feet above the level of the sea so lately as since the commencement of the Tertiary times; that the Purbeck beds of the upper oolite are in themselves the memorials of an enormous lapse of time; that, since a forest in a thousand years can scarce produce more than two or three feet of vegetable soil, each dirt-bed is the work of hundreds of centuries. What shall we say when it tells us that the delta of the Mississippi could only be formed in many tens of thousands of years, and yet that is only as yesterday when compared with the date of the inland terraces; that the recession of the Falls of Niagara from Queenstown to the present site consumed thirty thousand years; that if the depression of the carbonif erous strata of Nova Scotia took place at the rate of four feet in a century, there were demanded 375,000 years for its completion-such a movement in the upward direction would have raised Mont Blanc; that it would take as great a river as the Mississippi two millions of years to convey into the Gulf of Mexico as much sediment as is found in those strata. Such statements may appear to us, who with difficulty shake off the absurdities of the patristic chronology, wild and impossible to be maintained, and yet they are the conclusions that the most learned and profound geologists draw from their reading of the book of Nature.

respects the

Thus, as respects the age of the earth and her relations in time, we Summary as approach the doctrine of the Orientals, who long ago ascertainworld in time. ed that the scales of time and of space correspond to each other. More fortunate than we, they have had but one point of resistance to encounter, but that resistance they met with dissimulation, and

THE SUCCESSION OF WORLDS.

573

not in an open way. They attempted to conceal the tendency of their doctrine by allying or affiliating it with detected errors. According to their national superstition, the earth is supported on the back of an elephant, and this on a succession of animals, the last of which is a tortoise. It is not to be supposed that the Brahmans, who wrote commentaries on the Surya Siddhanta, should for a moment have accepted these preposterous delusions-that was impossible for such great geometers; yet led, perhaps, by a wish to do nothing that might disturb public feeling, they engaged in the hopeless task of showing that their profound philosophical discoveries were not inconsistent with the ancient traditions; that a globular and revolving earth might be sustained on a descending succession of supporting beasts. But they had the signal advantage over us that those popular traditions conceded to them that limitless time for which we have had to struggle.

universe.

The progression of life on the surface of our planet is under the guidance of preordained and resistless law-it is affiliated with The life of the material and correspondingly changing conditions. It suggests that the succession of organic forms which, in a due series, the earth's surface in the long lapse of time has presented, is the counterpart of a like progress which other planets in the solar system exhibit in myriads of years, and leads us to the conception of the rise, development, and extinction of a multiplicity of such living forms in other systems-a march of life through the universe, and its passing away.

Multiplicity of

succession of

Magnitudes and times, therefore, go parallel with one another. With the abandonment of the geocentric theory, and of the doctrine of the human destiny of the universe, have vanished the unworthy hypotheses of the recent date of creation and the approaching end of all things. In their stead are substituted more noble ideas. The multiplicity of worlds in infinite space leads to the conception of worlds implies a succession of worlds in infinite time. This existing uni- worlds. verse, with all its splendors, had a beginning, and will have an end; it had its predecessors, and will have its successors; but its march through all its transformations is under the control of laws as unchangeable as destiny. As a cloud, which is composed of myriads of separate and isolated spherules of water, so minute as to be individually invisible, on a summer's afternoon changes its aspect and form, disappearing from the sky, and being replaced in succeeding hours by other clouds of a different aspect and shape, so the universe, which is a cloud of suns and worlds, changes in the immensity of time its form and fashion, and that which is contemporary with us is only an example of countless combinations of a like kind, which in ancient times have one after another vanished away. In periods yet to come the endless succession of metamorphoses will still go on, a series of universes to which there is no end.

574

THE EUROPEAN AGE OF REASON.

CHAPTER XXIV.

THE EUROPEAN AGE OF REASON-(Continued).

THE NATURE AND RELATIONS OF MAN.

Position of Man according to the Heliocentric and Geocentric Theories.

OF ANIMAL LIFE.-The transitory Nature of living Forms.-Relations of Plants and Animals.—Animals are Aggregates of Matter expending Force originally derived from the Sun. THE ORGANIC SERIES.-Man a Member of it.-His Position determined by Anatomical and Physiological Investigation of his Nervous System.-Its triple Form: Automatic, Instinctive, Intellectual.

The same progressive Development is seen in individual Man, in the entire animal Series, and in the Life of the Globe.-They are all under the Control of an eternal, universal, irresistible Law.

The Aim of Nature is intellectual Development, and human Institutions must conform thereto. Summary of the Investigation of the Position of Man.-Production of Inorganic and Organic Forms by the Sun.-Nature of Animals and their Series.-Analogies and Differences between them and Man.-The Soul.-The World.

the heliocentric

theory.

WHEN the ancient doctrine of the plurality of worlds was restored The apparent po- by Bruno, Galileo, and other modern astronomers, the resition of man on sistance it encountered was mainly owing to its anticipated bearing on the nature and relations of man. It was said, if round our sun, as a centre, there revolve so many planetary bodies, experiencing the changes of summer and winter, day and night-bodies illuminated by satellites, and perhaps enjoying twilight and other benefits such as have been conferred on the earth-shall we not consider them the abodes of accountable, perhaps of sinful, beings like ourselves? Nay, more; if each of the innumerable fixed stars is, as our sun, a central focus of light, attended by dark and revolving globes, is it not necessary to admit that they also have their inhabitants? But among so many families of intelligent beings, how is it that we, the denizens of an insignificant speck, have alone been found worthy of God's regard? It was this reasoning that sustained the geocentric theory, and made the earth the centre of the universe, the most noble of created things; the sun, the moon, the stars, being only ministers for the service of man. But, like many other objections urged in that memorable conflict, this The fallacy was founded on a misconception, or, rather, on imperfect knowlof that is edge. There may be an infinity of worlds placed under the mechanical relations alluded to, but there may not be one among them that can be the abode of life. The physical conditions under which organization is possible are so numerous and so strictly limited that the chances are millions to one against their conjoined occurrence. In a religious point of view, we are greatly indebted to Geology for

ory.

objections

NATURE OF ANIMALS.

nished by Ge

575 the light it has cast on this objection. It has taught us that Evidence furduring inconceivable lapses of time our earth itself contained ology. no living thing. These were those preorganic ages to which reference was made in the last chapter. Then, by slow degrees, as a possibility for existence occurred, there gradually emerged one type after another. It is but as yesterday that the life of man could be maintained.

nature of liy

Only in the presence of special physical conditions can an animal exist. Even then it is essentially ephemeral. The life of it, as The transitory a whole, depends on the death of its integrant parts. In a ing forms. waterfall, which maintains its place and appearance unchanged for many years, the constituent portions that have been precipitated headlong glide finally and forever away. For the transitory matter to exhibit a permanent form, it is necessary that there should be a perpetual supply and also a perpetual removal. So long as the jutting ledge over which the waters rush, and the broken gulf below that receives them, remain unchanged, the cataract presents the same appearance. But variations in them mould it into a new shape; its color changes with a clear or a cloudy sky; the rainbow seen in its spray disappears when the beams of the sun are withdrawn.

So in that collection of substance which constitutes an animal; whatever may be its position, high or low, in the realm of life, there is a perpetual introduction of new material and a perpetual departure of the old. It is a form, rather than an individual, that we see. Its permanence altogether depends on the permanence of the external conditions. If they change it also changes, and a new form is the result.

An animal is therefore a form through which material substance is visibly passing, and suffering transmutation into new prod- Characteristics ucts. In that act of transmutation force is disengaged. That of animal life. which we call its life is the display of the manner in which the force thus disengaged is expended.

A scientific examination of animal life must include two primary facts. It must consider whence and in what manner the stream Matter and of material substance has been derived, in what manner and force. whither it passes away. And, since force can not be created from nothing, and is in its very nature indestructible, it must determine from what source that which is displayed by animals has been obtained, in what manner it is employed, and what disposal is made of it eventually.

rived from

The force thus expended is originally derived from the sun. Plants are the intermedium for its conveyance. The inorganic mate- Force is derial of a saline nature entering into their constitution is obtained the sun. from the soil in which they grow, as is also, for the most part, the wa ter they require; but their organic substance is derived from the surrounding atmosphere, and hence it is strictly true that they are condensations from the air.