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bral column terminating in a brain-protecting skull, and that in the acanth, celecanth, and dipterian families, they had the limb-like fins. In the upper part of the system, the earliest reptiles have the first-known traces of the typical foot, with its five digits. Higher still, in one of the deposits of the Trias, we are startled by what seems to be the impression of a human hand of an uncouth massive shape, but with thumbs apparently set in opposition, as in man, to the other fingers. We next trace the type upwards among the wonderfully developed reptiles of the Secondary periods. Then among the mammals of the Tertiary ages, higher and yet higher forms appear; the mute prophecies of the coming being will each approach clearer, fuller, more expressive, and at length receive their fulfilment in* the advent of man.
All this of course is viewed in a very different light by the Transmutationists, with whom it is obviously essential to deny any plan in the general arrangements of the organic world. For if it be conceded that there is a plan, this would necessarily imply a presiding intelligent mind, able to arrange and carry out the plan ; whereas the very essence of their system is that all living beings are the result of a non-intelligent sequence of events—of accidental circumstances benefiting and improving 'favoured' races, and leaving the rest to perish.
All these organic similarities and homologues of parts are with them evidences of descent. If the placoidal fishes of the upper Silurian have fins which were homologues of the fore and hinder limbs of quadrupeds, thoy interpret this that the fish is the ancestor of the quadruped, and that the quadruped derived his limbs from the fins of
* Testimony of the Rocks.
the fish. In the tail of the cow, giraffe, fox, lorse, &c., they see the tail of the fish worked up' for these different animals; modified, and altered indeed, but still made out of the fish's tail : and thus similitudes and homologues are all family-marks, and all bespeak one ancestral origin.
When several characters,' says Mr Darwin, let them be ever so trifling, occur together throughout the large group of beings having different habits, we may feel almost sure on the theory of descent, that the character has been inherited from a common ancestor' (458).
Mr Darwin might have said more than this, for 'on the Theory of Descent,' that is, taking for granted that that Theory is true, we may be quite sure that these characters’ have been inherited from a common ancestor. The postulate, however, is not conceded, and Mr Darwin has first to prove that his Theory is true.
However, thus more at length does he explain to us his views on this particular branch of his Theory :-.
We have seen that the members of the same class, independently of their habits of life, resemble each other in the general plan of their organization. This resemblance is often expressed by the term 'unity of type,' or by saying that the several parts and organs in the different species of the class are homologues. The whole subject is included under the term morphology. What can be more curious than that the hand of a man formed for grasping, that of a mole for digging, the leg of a horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include similar bones, in the same relative position? The parts may change to almost any extent in form and size, and yet they always remain connected together in the same order. We never find, for instance, the bones of the arm and forearm, or of the thigh and leg, transposed. Hence the same name can be given to the homologous bones in widely different animals.
*Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility, or hy doctrine of final causes. On the ordinary view of the independent creation of each being we can only say that it is--that it has so pleased the Creator to construct each animal and plant.'
“The explanation is manifest on the theory of Natural Selection of successive slight modifications—in changes of this nature there will be little or no tendency to modify the original pattern, or to transpose parts--the bones of the limbs might be shortened or widened to any extent, and become gradually enveloped in thick membrane, so as to serve as a fin-or a webbed foot might have all its bones, or certain bones, lengthened to any extent, and the membrane connecting them increased to any extent, so as to serve as a wing, &c. If we suppose that the ancient progenitor, the archetype as it may be called, of all mammals had its limbs constructed on the general pattern, for whatever portion they served, we can at once perceive the plain signification of the homologous construction of the limbs throughout the whole class,' &c. (466-7).
This passage, which clearly explains the demands of the Theory on Morphology, shows also the necessary exclusion of creation from the system of the Transmutationists, who reject with disdain the idea of referring the commencement of life of an organized being to an operation and a power which our understanding cannot grasp. The whole reasoning, however, goes on the assumption that Natural Selection (or the sequence of Natural events) can perforin these operations, and execute these transformations which seem so easy to Mr Darwin, that it can shorten or widen limbs to any extent, and cover them with membranes so as to turn them into a fin; that a webbed foot can be metamorphosed into a wing, and that animals can be changed by this agency from fishes to quadrupeds, from quadrupeds to birds, &c. &c., ad libitum.
Let all this be granted, and the 'explanation is manifest;' but till it be proved, what is this but corroborating one assertion by another? And it is obvious that by taking for granted the thing to be proved any other hypothetical term might be substituted for Natural Selection, and might serve just as well for the argument. For instance, let the influence of the soil (the hypothesis of M. Trémaux) or the agency of the solar heat and light take the place of Natural Selection in the above passage, and it is obvious that either would do quite as well for Mr Darwin's explanation of morphology. Let us, argumenti gratia, say, That the solar influence has the power of changing the forms of organized beings, then on this Theory, in changes of this nature, there will be no tendency to change the original pattern,' for the agent must act on what it finds ready at hand.
But Mr Darwin tells us that it is hopeless to explain the homologues of morphology by the doctrine of utility and final causes; we therefore naturally suppose that he him. self is able to explain these changes which, he affirms, are effected by Natural Selection. Will he then undertake to describe to us in accurate scientific language, the process by which the wing of a bat, the eye of an eagle, the proboscis of an elephant, the galvanic battery of an electrical fish, or the heart of a mammifer, were constructed ; and
that not in general vague terms of development, plastic tendencies, slight modifications, generative variability,' &c., but in such clear anatomical, chemical, optical, or dynamic terms, as the case may require, so as to enable us to comprehend without any doubt how these marvellous structures were fabricated, and to know the whole process as satisfactorily as we know the structure of a watch or a steamengine?
Now, unfortunately, Mr Darwin has in another part of his book said, “it is most difficult to conjecture by what transitions organs could have arrived at their present state'(213).
If even conjecture is at fault here, an instrument which in Mr Darwin's hands has done such ample service, it must be utterly hopeless to ask for certainty; and if even imagination can do nothing, how can we look for a scientific exegesis? In short, it is manifest not only by this confession, but by the very nature of the question itself, that the learned author of the Theory has here come to a dead-lock; and therefore we beg leave to turn his own language upon himself, and to say nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class by Natural Selection and the Struggle for Life.'
But it seems that in our view of the case we can only say 'it pleased the Creator to construct each animal or plant.' In other words, we do not scruple to confess ‘we do not know;' we suppose we have reached the limits of knowledge when we come to a certain point, and there we stop; and we judge confessed ignorance to be far safer than pretended knowledge.
And what can be the ultimate advantage of attempting