Chapter VI (1)

The doctrine of evolution, according to Herbert Spencer, further considered.

In the last two preceding chapters I have examined what Mr. Spencer regards as the direct supports of the doctrine of evolution. I have now to consider the different orders of facts which, as he claims, yield to it indirect support. These are the facts derived from classification, from embryology, from morphology, and from distribution. An explanation is here needful of the sense in which he uses these respective terms, before the reader, who is not accustomed to them, is called upon to understand and appreciate the argument:

1. By classification is meant an arrangement of organic beings in some systematic manner, according to attributes which they have in common, and which may form the principle of a division into different classes or families. Pointing out that in the early history of botanical and zoölogical science the tendency was to make classifications according to a single characteristic, Mr. Spencer reminds us that later naturalists, by attending to a greater number of characteristics, and finally to the greatest number that can be found to be common to various classes of vegetable and animal organisms, have constructed systems of classification which, in place of a linear or a serial order, have exhibited the alliances of different groups, then the sub-groups, and the sub-sub-groups, so that the divergences and redivergences become developed, while the resemblances which obtain are preserved throughout the whole class. But it is at once apparent that, although classification, on whatever principle it is conducted, may be valuable as a means of fixing in the mind the resemblances or differences of structure that obtain in the different orders of organized beings, as, for example, among the vertebrate or the invertebrate animals, the flowering or the flowerless plants, the seeds naked or the seeds inclosed in seed-vessels, yet that any other system of classification, based upon other resemblances or differences which actually present means of grouping or separating the different families of organized beings, is just as valuable an aid in the investigation of facts. How far any classification affords an argument, or the means of constructing an argument, which will yield a support to the doctrine of evolution superior to that which it yields to the doctrine of special creations, is of course a question.

2. Embryology: This is the term employed to express that branch of inquiry which is concerned in a comparison of the increase of different organisms through the stages of their embryonic life, and in noting at different stages of this growth the characters which they have in common with each other; the resemblances of structure which at corresponding phases of a later embryonic stage are displayed by a less extensive multitude of organisms; and so on step by step, until we find the class of resembling embryos becoming narrower and narrower, and then we finally end in the species of which a particular embryo is a member. This process of tracing and eliminating embryonic resemblances is said to have "a profound significance"; because, beginning with a great multitude of resemblances between the embryonic development of different organisms, it reveals the divergences which they take on, and through every successive step we find new divergences, by means of which "we may construct an embryological tree, expressing the developmental relations of the organisms, resembling the tree which symbolizes their classificatory relations." We thus arrive at "that subordination of classes, orders, genera and species, to which naturalists have been gradually led," and which is said to be "that subordination which results from the divergence and redivergence of embryos, as they all unfold."[79] On this mode of comparing the embryonic development of different organized beings Mr. Spencer builds a scientific parallelism, which indicates, as he claims, a "primordial kinship of all organisms," and a "progressive differentiation of them," which justifies a belief in an original stock from which they have all been derived. In what way this method of investigation destroys or tends to destroy the hypothesis of special creations, or how it affords an important support to the doctrine of evolution, will be considered hereafter.[80]

3. Morphology, or the science of form, involves a comparison of the structure of different organisms in their mature state; an ascertainment of the resemblances between their structures, and of the community of plan that exists between them. Here, as in the aids derived from classification and embryology, it is claimed that the fundamental likenesses of forms of structure have a meaning which is altogether inconsistent with the hypothesis of predetermined typical plans pursued throughout immensely varied forms of organisms.

4. Distribution: This is the term applied to the phenomena exhibited by the presence of different organisms in different localities of the globe; or, as Mr. Spencer phrases it, "the phenomena of distribution in space." These phenomena are very various. Sometimes, it is said, we find adjacent territories, with similar conditions, occupied by quite different faunas. In other regions, we find closely allied faunas in areas remote from each other in latitude, and contrasted in both soil and climate. The reasoning, as given by Mr. Darwin and adopted by Mr. Spencer, is this: that "as like organisms are not universally or even generally found in like habitats, nor very unlike organisms in very unlike habitats, there is no predetermined adaptation of the organisms to the habitats." "In other words," Mr. Spencer adds, "the facts of distribution in space do not conform to the hypothesis of design." The reason why they do not is claimed to be that there are impassable barriers between the similar areas which are peopled by dissimilar forms; whereas there are no such barriers between the dissimilar areas which are peopled by dissimilar forms. The conclusion is, "that each species of organism tends ever to expand its sphere of existence--to intrude on other areas, other modes of life, other media." That is to say, there is a constant competition among races of organisms for possession of the fields in which they can find the means of subsistence and expansion; and this leads to new modes of existence, new media of life, new structures and new habitats.

The reader can now retrace his steps, and advert to the facts that are relied upon, under the four heads of the argument:

1. With regard to the argument derived from classification: it is to be observed that any system of classification is in a certain sense artificial, and at all events is manifestly conventional. But, in order that no injustice may be done to this branch of the argument for evolution, I shall state it in its full force. The classifications which naturalists make of the different organized beings according to their resemblances and differences reveal the fact of unity amid multiformity. This fact it is said points to propinquity of descent, "which is the only known cause of the similarity of organic beings." It is the bond, hidden indeed by various degrees of modification, but nevertheless revealed to us by the classifications which display the resemblances. Again, we have, it is said, in the influence of various conditions of animated organisms, "the only known cause of divergence of structure." Classification reveals to us these divergences. We have, then, the bond of resemblances which indicate propinquity of descent, and the divergences of structure produced by varying conditions of life. Put the two together, and we have remarkable harmonies of likenesses obscured by unlikenesses; and to this state of facts it is claimed that no consistent interpretation can be given, without the hypothesis that the likenesses and the unlikenesses were produced by the evolution of organisms out of organisms by successive generation, through a great lapse of time.

This argument contains no inconsiderable amount of assumption. While it may be true that some naturalists do not assign any cause for the similarity which obtains among organic beings excepting their descent from a common ancestral stock, it is not true that the similarity of structure is inconsistent with the hypothesis of another cause, namely, the adoption of a general plan of structure for a large class of organisms, and an intentional variation in those parts of structure which mark the divisions of that class into species that are very unlike. It is true that evolutionists treat with scorn the idea of a pattern of structure followed throughout a class of animals, but made by designed adaptations to coalesce with differences that mark the peculiarities which distinguish one organism of that class from all the others. Mr. Spencer, for example, observes that "to say that the Creator followed a pattern throughout, merely for the purpose of maintaining the pattern, is to assign a motive which, if avowed by a human being, we should call whimsical."

Let us now follow this mode of disposing of the hypothesis of special creations, by adverting to some of the facts that are adduced in its summary condemnation; and, although the passage which I am about to quote is found in Mr. Spencer's work under the head of morphology, the illustration applies equally well to his argument from classification. Speaking of fundamental likenesses of structure, he says: "Under the immensely varied forms of insects, greatly elongated like the dragon-fly, or contracted in shape like the lady-bird, winged like the butterfly, or wingless like the flea, we find this character in common--there are primarily twenty segments. These segments may be distinctly marked, or they may be so fused as to make it difficult to find the divisions between them. This is not all. It has been shown that the same number of segments is possessed by all the _Crustacea_. The highly consolidated crab, and the squilla with its long, loosely-jointed divisions, are composed of the same number of somites. Though, in the higher crustaceans, some of these successive indurated rings, forming the exo-skeleton, are never more than partially marked off from each other, yet they are identifiable as homologous with segments, which, in other crustaceans, are definitely divided. What, now, can be the meaning of this community of structure among these hundreds of thousands of species filling the air, burrowing in the earth, swimming in the water, creeping about among the sea-weed, and having such enormous differences of size, outline, and substance, as that no community would be suspected between them? Why, under the down-covered body of the moth and under the hard wing-cases of the beetle, should there be discovered the same number of divisions as in the calcareous framework of the lobster? It can not be by _chance_ that there exist just twenty segments in all these hundreds of thousands of species. There is no reason to think it was _necessary_, in the sense that no other number would have made a possible organism. And to say that it is the result of _design_--to say that the Creator followed this pattern throughout, merely for the purpose of maintaining the pattern--is to assign a motive which, if avowed by a human being, we should call whimsical. No rational interpretation of this, and hosts of like morphological truths, can be given except by the hypothesis of evolution; and from the hypothesis of evolution they are corollaries. If organic forms have arisen from common stocks by perpetual divergences and redivergences--if they have continued to inherit, more or less clearly, the characters of ancestral races, then there will naturally result these communities of fundamental structure among extensive assemblages of creatures, that have severally become modified in countless ways and degrees, in adaptation to their respective modes of life. To this let it be added that, while the belief in an intentional adhesion to a predetermined pattern throughout a whole group is totally negatived by the occurrence of occasional deviations from the pattern, such deviations are reconcilable with the belief in evolution. As pointed out in the last chapter, there is reason to think that remote ancestral traits will be obscured more or less according as the superposed modifications of structure have or have not been great or long maintained. Hence, though the occurrence of articulate animals, such as spiders and mites, having fewer than twenty segments, is fatal to the supposition that twenty segments was decided on for the three groups of superior _Articulata_, it is not incongruous with the supposition that some primitive races of articulate animals bequeathed to these three groups this common typical character--a character which has nevertheless, in many cases, become greatly obscured, and in some of the most aberrant orders of these classes quite lost."[81]

Whatever may be the explanation suggested by one or another hypothesis as to the mode in which this uniformity of structure came to exist, it is certain that it does exist. Twenty segments are found in hundreds of thousands of species which are immensely different from each other in size, outline, substance and modes of existence. Here, then, is a plan. There is a pattern, on which all these different organisms are constructed with a common peculiarity. It is averred that this could not have been the result of design, because this would be to impute to the Creator a whimsical motive, namely, that he followed the pattern throughout a vast group of different organisms merely for the purpose of following it. On the contrary, it may be contended that this uniformity of plan, this repeated pattern, affords the highest probable evidence of design; and that the supposed whimsicality of motive will entirely disappear as soon as we reach a purpose which may have had very solid reasons for this uniformity of structure. When we reason about the works of the Creator, we are reasoning about the methods of a being who, we must suppose, is governed by a purpose in all that he does. In reasoning about the methods of such a being, it is entirely unphilosophical to suppose that he has done anything merely for the sake of doing it, or for the sake of exercising or displaying his powers in repetitions that had no practical value. In order to reason consistently with the supposed attributes of the Creator, we should endeavor to find the value of any given pattern which we discover in a certain very large class of organisms differing widely from each other in other respects; and in order to find that value it is by no means essential to make out that the particular plan of construction was necessary to the making of any organism whatever. The true question is, not whether twenty segments were necessary to the construction of any organism, but whether, in each of the different species, this peculiar number of divisions was useful to each particular organism. If naturalists of the evolution school, instead of looking at everything through the medium of a certain theory, would in their dissection, for example, of the framework of the lobster, the body of the moth, and the body of the beetle, furnish us with facts which would show that these twenty divisions are of no use either for strength, or resistance, or suppleness, or adaptation to what is contained within them, we should have a body of evidence that could be claimed as tending to overthrow the hypothesis of intentional design. They might then speak of the repetition of this pattern as whimsical, upon the hypothesis that it was a repetition by design. But so little is done by this class of naturalists to give due consideration to the value of such repetitions, and so little heed is paid to the truth that the Creator does nothing that is useless--a truth which all sound philosophy must assume, because it is a necessary corollary from the attributes of the Creator--that we are left without the aid which we might expect from these specialists in natural science. Is it, then, impossible to discover, or even to suggest, that for each of these organisms this number of twenty divisions had a value? If they were of no value, we may safely conclude that they would never have existed, unless we ignore the hypothesis of infinite wisdom and skill. That hypothesis is a postulate without which we can not reason on the case at all. With it, we have as a starting-point the conception of a being of infinite perfections, who does nothing idly, nothing from whim, nothing from caprice, and nothing that is without value to the creature in which it is found. So that, while we can not in all cases as yet assign that value, we have the strongest reasons for believing that there is a value; and, instead of asserting that an extensive community of structure throughout a great branch of the animal kingdom has no meaning excepting upon the doctrine of evolution, it is the part of true science to assume that it may have another meaning, and to discover if possible what that other meaning is. This is the part of true science, because it is the part of sound philosophy. There is another remark to be made upon Mr. Spencer's reasoning on this particular case of a community of pattern. He says that it can not be imputed to _chance_. It was, then, either an intentional design, or it came about through the process of descent "from common stocks, which process was at the same time producing perpetual divergences and redivergences." Without turning aside for the present to ask from how many common stocks, it may be shown as in the highest degree probable that the occasional deviations from the pattern did not arise by the evolution process, because that process has in itself an element of chance which is fatal to the theory. The assertion is that "an intentional adhesion to a predetermined plan throughout a whole group is totally negatived by the occurrence of occasional deviations from the pattern." Let this assertion be examined first in the light of facts, and secondly by the absence of facts.

The hypothesis is that some primitive race of articulated animals, possessed by some means of the twenty segments, transmitted this ancestral trait to hundreds of thousands of species having no community of structure in other respects. Unfortunately for the theory, no figures can measure the chances against the preservation of a single pattern through such a multitude of differing organisms descending from a common stock. Infinity alone can express the chances against such a result. While, according to the theory, the deviations from the original type were constantly working out new organisms of the most diversified forms, until there came to be hundreds of thousands of new species differing from each other in all but this one peculiarity--a diversity which is supposed to have been caused by the fundamental law of evolution--how did it happen that the same law did not break this uniformity of articulation? If it was potent enough to differentiate the enormous multitude of these animals in all other traits, why did it not vary the number of segments with which the primitive race was endowed? Is the law of evolution limited or unlimited? If it is limited in its effects, then there are patterns of animal structure which it has not modified, and the presence of which in hundreds of thousands of different species must be explained as a form of structure designed for some end that was to be common to a great multitude of different beings. If the law of evolution was unlimited in its power, then the community of pattern has had to undergo chances of destruction or discontinuance that are immeasurable; as there can be no measure which will represent to the mind the infinitely diversified and innumerable causes that have produced the dissimilarities which compel a classification into the different species, upon the hypothesis of their descent from a common stock. Grant, too, for the purpose of the argument, that the occasional deviations from the pattern of twenty segments, producing a few groups with a smaller number of articulations, are reconcilable with the belief that some later ancestral form became endowed with the smaller number which it transmitted to its descendants. How came that later ancestral form to be endowed with the smaller number of segments? Was there a still more remote ancestral race, which in some way became possessed of the smaller number, or did the spiders and the mites, in the countless generations of evolution, branch off from ancestral races having the full number of twenty segments? Upon either supposition, what an infinity of chances there were, against the natural selection of the smaller number, and against its preservation as the unvarying type of articulation found in the spiders and the mites! The supposition that the number of twenty segments was decided on for the three groups of superior _Articulata_ for the mere sake of adhering to a pattern is doubtless unphilosophical. But it is not unphilosophical to suppose that whatever amount of articulation is found in each species was given to it because in that species it would be useful. If in some of the most aberrant orders of these animals the articulation is greatly obscured, or not found at all, the conclusion that it was not needed, or not needed in a like degree, is far more rational than the theory which commits the particular result to an infinity of chances against it; or which supposes it to have been worked by a process that might have produced a very different result, since it can not be claimed that natural selection works by methods of which any definite result can be predicated more than another.

Thus far I have considered Mr. Spencer's argument from the _Articulata_ in the light of the facts that he adduces. Let us now test it by the absence of facts. In a former discussion, I have asked for facts which show, aside from the theory, that any one species of animal, distinctly marked as a continuing type, is connected by intermediate types or forms with any pre-existing race of another character. Take this class of the articulated animals, said to be of hundreds of thousands of different species having no community of form but this of articulation, and now known as perfect organisms, each after its kind. What naturalist has discovered the continuity of lives with lives, which would furnish the steps of descent of any one of this species from an antecedent and a different species? It is very easy to construct a theory, and from it to argue that there must have been intermediate links, which, if discovered, would show the continuity of lives from lives which the descent of one organism from another necessarily implies. To a certain extent, within certain limits, the sub-groups and the sub-sub-groups of the articulated class of animals, which classification or morphology reveals, may lay the foundation for a theoretical belief in an ancestral stock from which the different and now perfect forms of these distinct animals may have become developed by successive changes of structure. But the extent to which connected changes can be actually traced in the animal kingdom is extremely limited; and the important practical question is whether any one fact, or class of facts, has been discovered which will warrant the belief that beings of totally dissimilar forms and habits of life have, without any design, been evolved by the ordinary process of successive generation, through the operation of causes that have gradually modified the structure in all respects save one, and have at the same time enabled or allowed that one peculiarity of structure to escape from the influences which have modified both structure and modes of life in every other respect. Why, for example, upon the hypothesis of descent from a common stock, has that stock deviated under the influences of natural selection into the lobster, the moth, and the beetle, and yet the community of twenty segments of articulation has entirely escaped the effect of those influences? No reason can be assigned for the fact that it has escaped those influences, excepting that it was originally designed, and was impressed upon the proto-typical stock with such force as to place it beyond the reach of all such causes of modification as those which are ascribed to natural or sexual selection. Without the latter supposition, those causes were just as potent to bring about a modification in the number of articulations as they were to bring about all the astonishing diversities of structure and modes of life that we see, and therefore the most probable conclusion from the fact of this uniformity of the twenty segments is, that there was a barrier placed in this whole class of organisms, which has limited the modifying force of the supposed process of evolution, for the reason of some peculiar utility in this plan of articulation.

Perhaps it will be said that the process of evolution itself tends to the preservation of whatever is most useful, while the modifications are going on which develop new organs and new structures; and that thus, in the case before us, the twenty segments have been preserved throughout an enormous group by one of the fundamental laws of evolution, so that, if there is any peculiar utility in the twenty segments, that utility has been answered by the very process of gradual descent of one organism from another. But the difficulty with this reasoning is, that while it assumes for the modifying influences of natural and sexual selection a range of fortuitous causes sufficient to change the ancestral type into the acquisition of vastly diversified organs, powers, and modes of existence, so as to constitute new animals, it yet assumes that, by some recognition of a superior and paramount utility in the particular number of segments, the law of evolution has preserved that number from the influence of causes which have changed everything else. Now, the range of causes which was sufficiently varied, accidental, long-continued and complex to produce the diversities of structure in all other respects, by the infinitely modifying influences which have developed new organs and new modes of existence, must also have been of a sufficiently varied, accidental, long-continued, and complex character to have broken this plan of the twenty segments, unless we suppose that in some mysterious and inexplicable manner the different generations of these beings were endowed with some kind of sagacity which would enable them to strive for the preservation of this one peculiarity, or unless we suppose that Nature was ever on the watch to guard them from its destruction or variation, on account of its peculiar utility. The first supposition is not in accordance with the evolution theory; for that theory rejects all idea of conscious exertion on the part of any of the organisms. The second supposition leads us at once to the inquiry, how came it to be imposed upon a whole group of beings as a law of nature, that whatever utility of structure was of paramount importance to the whole group should be preserved against the modifying influences that were to produce species differing absolutely from each other, through hundreds of thousands of varieties, in every other feature of their existence? Can we get along here without the hypothesis of design? And, if there was such design, how does the fact of this uniformity amid such diversity become an argument against the hypothesis of a Creator? Or, how does it tend to displace the hypothesis of special creations, when we find that the very process of so-called evolution has failed to break the uniformity of a pattern that is conceded not to have been the result of chance, although that pattern was exposed to just as many and as powerful causes of modification as those which are assumed to have brought about the modifications in every other feature of the animal existence? The truth would seem to be, that the uniformity amid so great a diversity was either the result of a design which placed it out of the reach of all the modifying influences, or else it has, by a most incalculable result, escaped from the effect of those influences by a chance in which the ratio of one to infinity can alone measure the probability of such an escape.

Let us now advert to another of Mr. Spencer's illustrations of the futility of the "supernatural" and of the rationality of the "natural" interpretation.[82] This illustration is derived from what are called "homologous" organs; and the particular instance selected is the vertebral column.[83] There are creatures, such as snakes, a low order of the vertebrate kingdom, in which the bony axis is divided into segments of about the same dimensions from end to end, for the obvious advantage of flexibility throughout the whole length of the animal. But in most of the higher vertebrata, some parts of this axis are flexible and others are inflexible; and this is especially the case in that part of the vertebral column called the sacrum, which is the fulcrum that has to bear the greatest strain to which the skeleton is exposed, and which is yet made not of one long segment or vertebra, but of several segments "fused together." Mr. Spencer says: "In man there are five of these confluent sacral vertebræ; and in the ostrich tribe they number from seventeen to twenty. Why is this? Why, if the skeleton of each species was separately contrived, was this bony mass made by soldering together a number of vertebræ like those forming the rest of the column, instead of being made out of one single piece? And why, if typical uniformity was to be maintained, does the number of sacral vertebræ vary within the same order of birds? Why, too, should the development of the sacrum be the roundabout process of first forming its separate constituent vertebræ, and then destroying their separativeness? In the embryo of a mammal or bird, the substance of the vertebral column is, at the outset, continuous. The segments that are to become vertebræ, arise gradually in the midst of this originally homogeneous axis. Equally in those parts of the spine which are to remain flexible, and in those which are to grow rigid, these segments are formed, and that part of the spine which is to compose the sacrum, having passed out of its original unity into disunity by separating itself into segments, passes again into unity by the coalescence of these segments. To what end is this construction and reconstruction? If, originally, the spine in vertebrate animals consisted from head to tail of separate movable segments, as it does still in fishes and some reptiles--if, in the evolution of the higher vertebrata, certain of these movable segments were rendered less movable with respect to each other, by the mechanical conditions to which they were exposed, and at length became relatively immovable--it is comprehensible why the sacrum formed out of them should continue ever after to show more or less clearly its originally segmented structure. But on any other hypothesis this segmented structure is inexplicable."

We here see the predominating force of a theory which refuses all possible rationality to any hypothesis but its own. The confident tone with which facts are arrayed and are then pronounced inexplicable upon any other hypothesis than that which the writer asserts, without one scintilla of proof of their tendency to exclude every other supposition, renders the refutation of such reasoning a wearisome task. But there is here one plain and sufficient answer to the whole of the supposed difficulty. The evolution theory, in this particular application of it, is that originally there were vertebrate animals in which the spine consisted of separate movable segments from head to tail, as it does now in fishes and reptiles; but, as the higher vertebrata were evolved out of these lower forms, the movable segments were rendered less movable with respect to each other, and at length in the sacrum the segments became relatively immovable, and yet the originally segmented structure was retained in this part of the column, by force of the propinquity of descent from an antecedent type which had the whole column divided into movable segments. Upon no other hypothesis, it is asserted, is this result explicable.

Mr. Spencer's analysis of the sacrum is somewhat defective. It is, as he says, that part of the vertebrate column which in the higher class of vertebrate animals is, during fœtal life, composed, like all the rest of the column, of distinct vertebræ. These vertebræ, like the others, are flexible in the fœtal stage, but after birth they become coalesced or united into one piece, instead of remaining in separate pieces. Thus far, Mr. Spencer's description is, I am informed by anatomists, correct. But the questions which he propounds as if they were unanswerable upon the assumption that this change is inexplicable upon any other hypothesis than that of the evolution of the higher vertebrata out of the lower vertebrate animals, and that the sacrum, with its continuous piece, has retained the segmented outward form by force of the descent, demand closer consideration. Let us trace the process of formation in the human species, and then see what is the just conclusion to be derived from it. In the embryonic condition, the substance which is to form the vertebral column is continuous. As the fœtus is developed, this substance separates itself into the segments which are called vertebræ, and these segments remain flexible and movable throughout the column. After birth, the five lower segments become united in what is substantially one piece, but of course the marks of the original segments remain. This is what occurs in the origin and growth of the individual. Now, looking back to the period when this species of animal did not exist, and supposing it to have been specially created in the two related forms of male and female, endowed with the same process of procreation and gestation that has been going on ever since there is any recorded or traditionary knowledge of the race, why should not this very growth of the sacrum have been designed, in order to produce, after the birth of the individual, that relative rigidity which would in this part of the vertebral column be useful to an animal destined to an upright posture of the whole skeleton and to the habits and life of a biped? And, if we extend the inquiry to other species, why should we not expect to find, as in the case of an oviparous vertebrate like the ostrich, a repetition of the same general plan of forming the spinal column, for the same ultimate purpose, with such a variation in the number of original segments that are to constitute the sacrum as would be most useful to that bird, thus establishing for the ostrich a sacrum that in a reptile or a fish would not only not be required, but would be a positive incumbrance? Upon the hypothesis of special creations of the different species of vertebrate animals, every one of Mr. Spencer's questions, asked as if they were unanswerable, can receive a satisfactory solution. Thus, he asks, "Why, if the skeleton of each species was separately contrived, was this bony mass [the sacrum] made by soldering together a number of vertebræ like those forming the rest of the column, instead of being made [aboriginally] in one single piece?" The answer is, that in the establishment of the process of gestation and fœtal growth, if a human artificer and designer could have devised the process, he would have selected the very one that now exists, for certain obvious reasons. First, he would have designedly made the process to consist, in the embryo, of a division of the substance which was to form the vertebral column in a continuous and uniform division into segments, because the whole column is to have at first the flexibility that may be derived from such a division. Secondly, when the time was to arrive at which the formation of the sacrum, with its practical continuity of a single piece, was to commence, he would select the number of the lower vertebræ that would make a sacrum most useful to the particular species of animal, and would weld them together so as to give them the relative rigidity and action of a single piece. But as the whole formation is the result of a growth of the sacrum out of a part of the slowly forming column originally divided into vertebræ, the marks of these separate vertebræ would remain distinguishable, while they would cease to have the mechanical action of separate vertebræ.

Another of Mr. Spencer's questions is, "Why, if typical uniformity was to be maintained, does the number of sacral vertebræ vary within the same order of birds?" The answer is the same as that which assigns a reason for all other variations in the skeleton of animals of the same order but of different varieties, namely, the special utility of the variations in the number of sacral vertebræ that would be most useful in that variety. The typical uniformity maintained is a uniformity in the process of growth and formation, down to a point where the variations are to come in which mark one animal from another; and I have more than once had occasion to suggest that the typical uniformity, and its adaptation to the varying requirements of different beings, is the highest kind of moral evidence of the existence, wisdom, and power of a supreme artificer, and that it militates so strongly against the doctrine of evolution that, without more proof than can possibly be claimed for that doctrine, we ought not to yield to it our belief.

The theory that the original condition of all vertebrate animals was that of separate movable segments throughout the spinal column, as it is now in fishes and some reptiles, and that in the evolution of the higher vertebrates out of these lower forms, certain of these movable segments were rendered less movable with respect to each other by the mechanical conditions to which the successive generations were exposed, until at length the sacrum was formed, is undoubtedly a theory that excludes all design of an infinite artificer, and all intention whatever. It is a theory which relegates the most special contrivances and the most exact adaptations to the fortuitous operation of causes that could not have produced the variations of structure and at the same time have preserved the typical uniformity. It is certainly a theory which we should not apply to the works of man, if we were investigating products which seemed to be the result of human ingenuity and skill, but of the origin of which we had no direct evidence. In such a case, we should not shut our eyes to the proofs of intentional variations and adaptation, or, if we did, our speculations would not be likely to command the assent of cultivated and sound reasoners. We may treat the works of Nature by a system of logic that we should not apply to the works of man, but if we do, we shall end in no tenable results. The principal and in fact the only essential distinction to be observed between the works of Nature and the works of man relates to the degree of power, intelligence, and skill in the actor. If we assume, as we must, that in the one case there was an actor, applying will, intelligence, and power to the properties of matter, and molding it into certain products and uses, and that in the other case there was no actor, but that all products and results are but the ungoverned effects of what are called natural laws in contradistinction to all intentional purposes, we must argue upon principles that are logically and diametrically inconsistent in themselves, and at variance with fundamental laws of reasoning.

I will now advert to an omission in Mr. Spencer's analysis of the sacrum, which overlooks one of the strongest proofs of intentional design afforded by that part of the spinal column. We have seen what was its general purpose and growth, and the process of its formation. We have now to note its variations in the male and the female skeleton. In the male, the sacrum, thus formed before birth, after birth answers to and performs its ultimate function of a comparatively rigid and inflexible piece of bone, and it is provided with no other special characteristic. In the female, on the contrary, there is a most remarkable adaptation of this piece to the function of maternity. While all the upper vertebræ of which this piece was originally composed are welded together after birth in the female as in the male, in the female the lowest segment of all remains for a certain time flexible relatively to the upper part of the sacrum, in order to admit of the necessary expansion of the pelvis during the passage of the infant from the womb of the mother. In the normal condition of females of all the vertebrate orders, this flexibility of the lower part of the sacrum continues while the period of possible maternity continues. If in any individual female it happens to be wanting during the period of possible conception, delivery can not take place without danger to the mother or the offspring, or both. Hence, in very bad cases, nature has to be assisted by extraordinary means. But in the normal condition of the female sacrum, this flexibility, so essential in the process of safe delivery, is always found, and its special purpose is known to every anatomist, while it has no existence in the structure of the male. Is this distinction to be accounted for by the same kind of reasoning that undertakes to account for all the other great distinctions between the related forms of male and female, which reproduce their kind by a common process of the sexual union, namely, that this division of male and female came about by a habit that resulted now in the production of a male and now in the production of a female, from tendencies that were ungoverned by any special purpose? Must we not conclude, however inscrutable are the causes that determine the sex of a particular infant, that the sexes themselves were specially ordained? And if they were specially ordained, how are we to account for the special construction and function of each of them, without the interposition of a special design? And when we find a structure in the female obviously designed for a special purpose, and not existing in the male, are we to conclude that some particular race of females, in some remote period of antiquity, among the countless generations of the vertebrata, found that this flexibility of the sacrum would be highly convenient to them, and, having adopted it as a habit, transmitted it, as a specially acquired peculiarity of structure, to their female descendants? This is all very well as a theoretical speculation, but as a speculation it is entirely defective, because it assigns the peculiarity of structure to a cause that could not have produced it. On the other hand, the hypothesis of its special creation assigns it to a cause that could have produced it, and its existence is among the highest of the multitudinous evidences of intentional design and special formation.

Wherein consists the irrationality of the hypothesis that a plan of construction was intentionally, and with supreme skill, framed for very different beings, to answer in each of them a common purpose? The asserted irrational character of this hypothesis consists in nothing but a denial that there was a Creator. It comes down to this, if it comes to anything: because, if we assume that there was a Supreme Being who took any care whatever of the complex and manifold product that we call nature--if we suppose that he ordained anything--we must suppose that his power to construct was boundless, and that a repetition of his plans wherever they would be useful, to answer the beneficent and diversified ends of infinite skill and benevolence, is just as much in accordance with the whole hypothesis of his attributes as it is to suppose that he caused anything whatever to exist. If we deny his existence, if we can not satisfy ourselves of it at all, if we suppose that nothing was ordained, nothing was created, but that all these diversified forms of animal organisms grew out of a protoplasmic substance, and that there was never any absolute commencement of organic life on the globe, or any absolute commencement of anything whatever, it is of course idle to speculate upon the adoption or preservation of patterns, as it is equally idle to pursue the theory of evolution through stages which at last end nowhere whatever.[84]

It may be well to cite Mr. Spencer's final summary of the general truths which he claims to be revealed by morphology, because it will enable the reader to see just where the logical inconsequence of his position occurs: "The general truths of morphology thus coincide in their implications. Unity of type, maintained under extreme dissimilarities of form and mode of life, is explicable as resulting from descent with modification; but is otherwise inexplicable. The likenesses disguised by unlikenesses, which the comparative anatomist discovers between various organs in the same organisms, are worse than meaningless if it be supposed that organisms were severally formed as we now see them; but they fit in quite harmoniously with the belief that each kind of organism is a product of accumulated modifications upon modifications. And the presence, in all kinds of animals and plants, of functionally useless parts corresponding to parts that are functionally useful in allied animals and plants, while it is totally incongruous with the belief in a construction of each organism by miraculous interposition, is just what we are led to expect by the belief that organisms have arisen by progression."[85]

Without expending much criticism upon the phrase "miraculous interposition," as a description of what takes place in special creation, it is sufficient to say that the act of special creation of a distinct organism is to be first viewed by itself, as if it stood alone in nature, and that it is like any other act of causing a new thing to exist which did not exist before. To this idea should be added the fact that in the creation of an animal organism there is involved the direct formation of a peculiar type of animal, with a capacity of producing other individuals of the same type through a process of generation. When, after having attained this conception of the act of special creation, and contemplated a single instance of the supposed exercise of such a power, we extend our inquiries, we find many other instances of the exercise of the same power; and then we observe a certain unity of type in some peculiarity of structure, maintained under extreme dissimilarities of form and mode of life. How, then, is this one similarity of pattern, amid such multiformity in other respects, "worse than meaningless," if we suppose that "organisms were severally framed as we now see them"? The very hypothesis that they were so severally framed carries in itself a meaning which can not be thus summarily ignored; because that hypothesis implies a power in the Creator to do just what we see. You may deny the power; but if you admit the existence of the infinite creating power, you are remitted to the inquiry into its probable methods; and you can no more say that the special creation of distinct organisms, with a certain unity amid a great multiformity, leaves the whole phenomena without a meaning, than you can say that any method which you can suggest is necessarily the only method which will afford a rational meaning in what we see. You must go the length of denying the entire postulate of a Creator, before you can be in a situation to deny the meaning that is involved in the idea of creation; for that idea implies an absolute power to apply a uniform pattern of structure to a whole class of organisms varied in all other respects. The theory that each kind of organism is a product of accumulated modifications upon modifications, without any special interposition to produce the modified and distinct forms, must be maintained on one of two suppositions: either that at some period there was an absolute commencement of organic life in some form, upon this globe, and that then all the other forms which we see were left to be evolved out of that one by the ungoverned accumulation of modifications upon modifications, or else that there was never any absolute commencement of organic life at any time, but that matter, by some peculiar property derived from some source that is not suggested, took on combinations which resulted in some crude form of animated organism, and that then the accumulations of modifications upon modifications followed from some process of generation by which the successive organisms became multiplied and varied. Of the former supposition, I understand Mr. Darwin to have been a representative naturalist. Of the latter, I understand Mr. Spencer to be an advocate. Upon what may be called the Darwinian doctrine, the idea of a Creator, causing to exist at some time some crude form of animal life, is admitted. Upon the Spencerian doctrine, which will be in this respect more closely examined hereafter, I do not see that the idea of a creating power comes in anywhere, either at the commencement of a series of organisms or at any point in that series. But, upon the logical proposition asserted in the passage last above quoted, it is obvious that, unless the idea of a Creator is absolutely denied, the presence of a unity of type amid any amount of dissimilarities of form and mode of life can not be pronounced to be without meaning, because the idea of a Creator implies a power to make that very unity amid the uniformity, which is asserted to be inexplicable without resorting to the theory that it was not made at all, but that it grew out of events over which no superintending or governing power was exercised. Upon this kind of dogmatic assertion there can be no common ground of reasoning.

The assumed incongruity between the facts and the hypothesis of a special creation of each organism is an incongruity that arises out of the assumption that such special creation was an impossibility. If once the idea of an infinite creating faculty is assumed as the basis of the reasoning, all seeming incongruity vanishes, and the probable method of that creating power must be determined by the preponderance of evidence. If the power is denied, we must grope our way through systems which impute everything to the properties of substance, without any suggestion of a source from which those properties were derived, and without anything to guide them but the tendencies implanted in them, we know not how or when, and of the origin of which we have not even a suggestion. Some of the speculations of Greek philosophers adverted to in a previous chapter may serve to show us what comes of the omission to conceive of power as abstracted from substance or its properties. The philosophy which first attained to this conception led the way to that conception of an Infinite Being, without whose existence and attributes all speculation upon the phenomena of nature leads to nothing. A belief in his existence and attributes must undoubtedly be attained by an examination of his works, if we set aside the teachings of revealed religion. But if we can not attain it, we have no better means for believing in the doctrine of evolution than we have for believing in any other method by which the phenomena of nature have become what they are.