« ПредыдущаяПродолжить »
naturally, and, under given circumstances, are constant. We class the brown and black bear as different species,—yet what differences do they present at all comparable to those which distinguish the mastiff from the spaniel, or the greyhound from the bull-dog ; or these again from the scent-hounds. So also the varieties of domestic fowls present as marked differences as those which distinguish many individuals of the parrot or grouse family, which are classified as distinct species.
Until the time of Lamarck, the scientific world generally accepted the definition of Linnæus, that “a species consisted of individuals, all resembling each other, and re-producing their like by generation.” This definition, though vague, had the merit of fixing, by an infallible test, the line of distinction, but it did not recognize the law of change, by which varieties are developed from the influence of external causes. Lamarck, observing that some fossil “ shells were so nearly allied to living species that it was difficult not to suspect that they had been connected by a common bond of descent," proposed to add to the above definition of Linnæus the following clause, viz: “so long as the surrounding conditions do not undergo changes sufficient to cause their habits, characters and forms, to change.” This addition was very good, inasmuch as it recognized the universal law of change, by which varieties are developed in every department of Nature, within fixed limits. Had Linnæus inserted it in his definition, it would have constituted the basis of a true development theory, and would have precluded the origin of the present transmutation hypothesis.
Lamarck, ignoring Linnæus' great test of distinction, and not duly appreciating Nature's great law of change, fixed his attention exclusively on the varieties, developed under this law; and by an unwarrantable generalization of facts, carefully observed, he broached the startling doctrine of progressive transmutation of species, by which the origin of Man, God's master-piece, has been derived from a monkey, through the successive evolutions of a primary monad. According to him, a short-legged bird, constantly desiring to catch fish to better advantage, gives rise to a race of long-legged waders.
In like manner, the camel-leopard has acquired its present shape, by constantly stretching out its neck to reach the higher branches of trees, as the lower ones became scarce. These fanciful lucubrations of Lamarck clearly indicate the origin of Mr. Darwin's hypothesis.
The anonymous author of the “ Vestiges of Creation,” which appeared in 1844, following closely in the tracks of Lamarck, introduced, as a principal element of change, the force of maternal volition, acting on the embryo, thereby transmuting it into a higher grade than its parent.
Mr. Darwin has somewhat modified these materialistic hypotheses, but it is doubtful whether he has much improved them. To get rid of the imputation, to which the others are liable, of making the orderly arrangement of nature the result of blind chance, he imagines the existence of some vague controlling power, called “Natural Selection,” equally blind and materialistic, operating solely through chance variations. He also attempts to get rid of another objection to Lamarck's theorywhich demands a continual creation of monads, by spontaneous generation, to supply the place of those which have been progressively advanced-by arguing that variation is not necessarily progressive, but that, in the struggle for existence, any animal, which has some slight advantage over his fellows, is “ naturally selected” for transmutation into some other form, perhaps not superior in organization. This supposition, if true, involves no change of principle, but only a slight difference in the partial working of the machinery of development. The fundamental principle of both hypotheses is the same, viz :—that the Animal Creation has been progressively developed, from the lowest to the highest form, from a Monad to Man.
Mr. Darwin's scheme of creation is based entirely upon the following assumptions :
1st. That “all the organic beings, extinct and recent, which have ever lived on this earth," are the modified descendants, by natural generation, of one common ancestor, and in this common descent, "all have been connected by the finest gradations." His argument for this assumption is an unwarrantable application of the maxim so often quoted by him, “Natura non facit saltum."
2d. As all animals are apt to vary, and have a tendency to increase beyond the means of subsistence, he assumes that some advantageous chance variation in an individual, transmitted to its posterity, has enabled them to root out their fellows, in the struggle for food, and has led, " as a consequence, to Natural Selection,” thus giving birth to new species, and causing “the extinction of less improved forms.” His argument for this assumption is based on a perverse generalization of the well-known fact, that all animals are capable of developing varieties,—and he supports it mainly by citing the great diversity of form produced in pigeons, and other animals, by a careful and judicious selection.
3d. His greatest assumption—and a monstrous one it isconsists in making this “Natural Selection,” which is the consequence of physical causes, the law-giving cause and controlling agent of creation, endowed with an all-wise and allprovident intelligence. He asserts that this “Power” has accumulated the slight accidental variations of individuals, from the beginning of time, preserving the good and rejecting the bad ; that it has, with consummate wisdom, directed these chance variations into many distinct lines of development, thereby creating new animals with new organs; that it has adapted them to their proper localities and proper functions ; endowed them with their necessary instincts; and distributed them into those distinct classes, orders, genera and species, which we now behold. The monstrous assumption that such an imaginary power exists in nature, being, at the same time, both the creature and the creator of physical law, is the pivot on which Mr. Darwin makes his hypothesis revolve, in order to meet any objection or to solve any difficulty.
On these three assumptions, Mr. Darwin founds what he calls his “theory," and against it we advance three objections.
1st. His “Natural Selection,” considered as an intelligent Agent, is not a vera causa.
20. His natural selection, considered as the consequence of physical law, is incompetent to produce the changes which he attributes to it.
3d. There is another cause, and a far more rational one, which accounts for the phenomena he seeks to explain.
These objections, which embrace the tests of a sound theory, will underlie all our remarks ; but the loose and desultory manner in which this book is written, abounding in repetitions and devoid of all sustained argument, forbids strict method in its review, and forces us, in some degree, to the necessity of like repetition.
We will now proceed to give some quotations, which will justify the accuracy of the above analysis, and will prove our author's theory to be, according to his own showing, merely a fanciful hypothesis.
He accounts for the origin of creation as follows :
“I believe that animals have descended from at most only four or five progenitors, and plants, from an equal or less number.—Therefore I should infer, from analogy, that probably all the organic beings which have ever lived on the earth have descended from some one pri. mordial form, into which life was first breathed.” p. 420.
This creed demands from us more Faith than the cosmogony of Moses.
In his introductory remarks, he says :
“As many more individuals are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it varies, however slightly, in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.” p. 12.
From this it is manifest that natural selection is made dependent upon “ chance."
At the conclusion of his work, while contemplating the present aspect of nature as having “ been produced by laws acting around us," he says :
“ These laws, taken in the largest sense, being Growth with Re-production; Inheritance, which is almost implied by re-production; Variability from the indirect and direct action of the external conditions of life, and from use or disuse;*- -a Ratio of Increase so high as to
* As an example of the modifying influence of “use and disuse," we give our author's method of accounting for the fact, that cows have no upper incisors.
lead to a Struggle for Life, and, as a consequence, to Natural Selection, entailing divergence of character and the extinction of less improved forms. Thus, from the war of nature, from famine and death, the most exalted object we are capable of conceiving, namely, the production (creation ?) of the higher animals, directly follows.” p. 425.
(The capitals are the author's, but the italics here and elsewhere are generally our own.)
From this it would appear that our author makes growth, variability, and a high ratio of increase, -all of which are results of external causes,-to be creative laws; and that “Natural Selection” is a consequence of one of these laws, viz., a high “Ratio of Increase.”
The term, "Natural Selection," upon which his whole scheme turns, is used very loosely by our author. At one time it expresses the beneficial effects of cross-breeding ; at another time it signifies the adaptabilty of animals or plants to certain conditions and localities ; and then again, it refers to sexual preference. In regard to this sexual natural selection, we will cite a single passage, more as a specimen of the kind of analogical reasoning with which the book is filled, than as a sample of the author's peculiar views of the production of new forms, by the “charms of the males.”
“ The rock-thrush of Guiana, birds of Paradise, and some others, congregate; and successive males display their gorgeous plumage, and perform strange antics before the females, which, standing by as spectators, at last choose the most attractive partner.- -If man can, in a short time, give elegant carriage and beauty to his bantams, according to his standard of beauty, I can see no good reason to doubt that female birds, by selecting, during thousands of generations, the most melodious or beautiful according to their standard of beauty, might produce a marked effect.”
But the idea of “Natural Selection,” which characterizes our author's hypothesis, is, that of an omnipotent, beneficial,
"The calf, for instance, has inherited teeth, which never cut through the gums of the upper jaw, from an early progenitor, having well developed teeth; and, we may believe, (credat Judæus,) that the teeth in the mature animal were reduced, during successive generations, by disuse, (!) or by the tongue and palate having been fitted, by natural selection, (1 !) to browse without their aid.” He adds, that Nature has thus taken pains to reveal “her scheme of modification, which, it seems, we wilfully will not understand.” We imagine that very few will wish to excuse themselves from the charge of wilful disbelief in such visionary schemes.