on this earth have descended," by the way of "natural selection," from a hypothetical unique instance of a miraculously created primordial form.

century, Lamarck in the first half of the present, Darwin in the second half. The great names to which the steady inductive advance of zoology has been due during those periods, have kept aloof from any hypothesis on the origin of species. One only, in connection with his paleontological discoveries, with his development of the law of irrelative repetition and of homologies, including the relation of the latter to an archetype, has pronounced in favor of the view of the origin of species by a continuously operative creational law; but he, at the same time, has set forth some of the strongest objections or exceptions to the hypothesis of the nature of that law as a progressively and gradually transmutational one.

Mr. Darwin rarely refers to the writings of his predecessors, from whom, rather than from the phenomena of the distribution of the inhabitants of South America, he might be supposed to have derived his ideas as to the origin of species. When he does allude to them, their expositions on the subject are

We are aware that Professor Owen and others, who have more especially studied the recently discovered astounding phenomena of generation summed up under the terms parthenogenesis and alternation of generations, have pronounced against those phenomena having, as yet, helped us "to penetrate the mystery of the origin of different species of animals," and have affirmed, at least so far as observation has yet extended, that "the cycle of changes is definitely closed;" that is, that when the ciliated "monad" has given birth to the "gregarina," and this to the "cercaria," and the "cercaria" to the "distoma,”—that the fertilized egg of the fluke-worm again excludes the progeny under the infusorial or monadic form, and the cycle again recommences.* But circumstances are conceivable,-changes of surrounding influences, the operation of some intermittent law at long intervals, like that inadequately represented. Every one studyof the calculating-machine quoted by the author of "Vestiges," under which the monad might go on splitting up into monads, the gregarina might go on breeding gregarinæ, the cercaria cercariæ, etc., and thus four or five not merely different specific, but different generic, and ordinal forms, zoologically viewed, might all diverge from an antecedent quite distinct form. For how many years, and by how many generations, did the captive polype-progeny of the Medusa aurita go on breeding polypes of their species (Hydra tuba), without resolving themselves into any higher form, in Sir John Dalyell's aquarium! The natural phenomena already possessed by science are far from being exhausted, on which hypotheses, other than transmutative, of the production of species by law might be based, and on a foundation at least as broad as that which Mr. Darwin has exposed in this essay.

We do not advocate any of these hypotheses in preference to the one of "natural selection," we merely affirm that this at present rests on as purely a conjectural basis. The exceptions to that and earlier forms of transmutationism which rise up in the mind of the working naturalist and original observer, are so many and so strong as to have left the promulgation and advocacy of the hypothesis, under any modification, at all times to individuals of more imaginative temperament; such as Demaillet in the last

President's Address to the British Association at Leeds, p. 27.

† See the beautiful work entitled, "Rare and Remarkable Animals of Scotland," 4to. vol. i. 1847, by Sir J. G. Dalyell.

ing the pages of Lamarck's original chapters (iii. vi. vii., vol. i., and the supplemental chapter of "additions" to vol. ii. of the "Philosophie Zoologique"), will see how much weight he gives to inherent constitutional adaptability, to hereditary influences, and to the operation of long lapses of time on successive generations, in the course of transmuting a species. The common notion of Lamarck's philosophy, drawn from the tirades which a too figurative style of illustrating the reciprocal influence of innate tendencies and outward influences have drawn upon the blind philosopher, is incorrect and unjust. Darwin writes:

"Naturalists continually refer to external conditions, such as climate, food, etc., as the only possible cause of variation. In one very limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the misseltoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other; it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the violation of the plant itself.

"The author of the Vestiges of Creation' would, I presume, say that, after a certain unknown number of generations, some bird had given birth to a woodpecker, and some plant to the misseltoe, and that these had been pro

would effect mutations somewhat more decided, but of the same character ? " *

Unquestionably not, replies Mr. Darwin:

sand generations would produce a marked effect, and adapt the form of the fox or dog to the catching of hares instead of rabbits, than that greyhounds can be improved by selection and careful breeding." t

duced perfect as we now see them; but this assumption seems to me to be no explanation, for it leaves the case of the co-adaptations of organic beings to each other and to their physical conditions of life untouched and unexplained."-P. 3. "To give an imaginary example from changes The last cited ingenious writer came to in progress on an island: let the organization the task of attempting to unravel the "mys- bits, but sometimes on hares, become slightly of a canine animal which preyed chiefly on rabtery of mysteries," when a grand series of plastic; let these same changes cause the num embryological researches had brought to ber of rabbits very slowly to decrease, and the light the extreme phases of form that the number of hares to increase; the effect of this higher animals passed through in the course would be that the fox or dog would be driven to of foetal development, and the striking anal- try to catch more hares; his organization, howogies which transitory embryonal phases of ever, being slightly plastic, those individuals a higher species presented to series of lower with the lightest forms, longest limbs, and best species in their permanent or completely de- eyesight, let the difference be ever so small, veloped state. He also instances the abrupt live longer, and to survive during that time of would be slightly favored, and would tend to departure from the specific type manifested the year when food was scarcest; they would by a malformed or monstrous offspring, and also rear more young, which would tend to incalled to mind the cases in which such mal- herit those slight peculiarities. The less fleet formations had lived and propagated the de- ones would be rigidly destroyed. I can see no viating structure. The author of "Ves-more reason to doubt that these causes in a thoutiges," therefore, speculates-and we think not more rashly or unlawfully than his critic has done on other possibilities, other conditions of change, than the Lamarckian ones; as, for example, on the influence of premature birth and of prolonged fœtation in es- Of course, prosaic minds are apt to bore tablishing the beginning of a specific form one by asking for our proofs, and one feels different from that of the parent. And does almost provoked, when seduced to the brink not the known history of certain varieties, of such a draught of forbidden knowledge such as that of M. Graux's cachemir-wooled as the transmutationists offer, to have the sheep, which began suddenly by malforma- Circean cup dashed away by the dry remark tion, show the feasibility of this view? of a president of the British Association:"The whole train of animated beings," "Observation of animals in a state of nature writes the author of "Vestiges of Creation," is required to show their degree of plasticity, or "are the results first, of an inherent impulse the extent to which varieties do arise: whereby in the forms of life to advance, in definite grounds may be had for judging of the proba times, through grades of organization ter- Bility of the elastic ligaments and joint-structures minating in the highest dicotyledons and of a feline foot, for example, being superinduced mammals; second, of external physical cir- upon the more simple structure of the toe with cumstances, operating re-actively upon the the non-retractile claw, according to the princentral impulse to produce the requisite pe- ciple of a succession of varieties in time." t culiarities of exterior organization, the This very writer has, however, himself adaptation of the natural theologian." But he, likewise, requires the same additional element which Mr. Darwin so freely invokes. "The gestation of a single organism is the Vestiges," to produce the teleological adapwork of but a few days, weeks, or months; tations. Professor Owen has pointed out but the gestation (so to speak) of a whole the numerous instances in the animal kingcreation is a matter involving enormous dom of a principle of structure prevalent spaces of time."... "Though distinctions throughout the vegetable kingdom, exempliadmitted as specific are not now, to ordinary fied by the multiplication of organs in one observation, superable, time may have a animal performing the same function, and power over these." Geology shows not related to each other by combination of successions of forms and grants enormous powers for the performance of a higher funcspaces of time within which we may believe tion. The invertebrate animals, according them to have changed from each other by to the professor, afford the most numerous the means which we see producing varieties. and striking illustrations of the principles Brief spaces of time admittedly sufficing to produce these so-called varieties, is it unrea*Vestiges of Creation, 8vo., 1846, p. 231. sonable to suppose that large spaces of time "On the Tendency of Species to form Varieties," etc., in Proceedings of the Linnean SociReports of the Juries Exhibition of the Works ety," 1858, p. 49. of All Nations, 8vo., 1852, p. 70. Address, p. 44.

66

suggested an operative cause in the development of organized beings of a different and opposite character to that conceived by

seg

which he has generalized as the "Law of that the more generalized structure is in a Irrelative Repetition." very significant degree, a characteristic of many extinct as compared with recent animals; and it may be readily conceived that specialization of structure would be the result of the progressive modification of any organ applied to a special purpose in the animal economy.

"We perceive," says he, "in the fact of the endoskeleton consisting of a succession of ments similarly composed-in the very power of enunciating special, general, and serial homologies an illustration of that law of vegetative or irrelative repetition, which is so much more conspicuously manifested by the segments of the We have cited these attempts to elucidate exoskeleton of the invertebrata: as, for ex- the nature of the organizing forces, to show ample, in the rings of the centipede and worm, the prevalent condition of the most advanced and in the more multiplied parts of the skeleton of the Echinoderms. The repetition of similar physiological minds in regard to the cause segments in the spinal column, and of similar of the successive introduction of distinct elements in a vertebral segment, is analogous to the repetition of similar crystals, as the result of the polarizing force in the growth of an inorganic body. Not only does the principle of vegetative repetition prevail more and more as we descend in the scale of animal life, but the forms of the repeated parts of the skeleton approach more and more to geometrical figures; as we see, for example, in the external skeletons of the echini and star-fishes; nay, the calcifying salt assumes the same crystalline figures which characterize it, when deposited and subject to the general polarizing force out of the organized body. Here, therefore, we have direct proof of the concurrence of such general all-pervading polarizing force, with the adaptive or special organizing force, in the development of an animal body." In addition, therefore, to the organizing principle, however explained, producing the special "adaptations," and admitted as the "second" power in the production of species by "Vestiges," Professor Owen states

"There appears also to be in counter-operation during the building up of such bodies, a general polarizing force, to the operation of which the similarity of forms, the repetition of parts, the signs of the unity of organization may be mainly ascribed; the platonic idea or specific organizing principle would seem," he adds, "to be in antagonism with the general polarizing force, and to subdue and mould it in subserviency to the exigencies of the resulting specific form."*

An index of the degree in which the polaric or irrelative repetitive force has operated is given by that character of the animal's organization which is expressed by the term of a more generalized structure." V. Baer pointed out that the structure was "more generalized," in the ratio of the proximity of the individual to the starting point of its existence. In proportion as the individual is subject to the action and re-action of surrounding influences, in other words, as it advances in life, does it acquire a more specialized structure-more decided specific and individual characters.† Owen has shown

Archetype of the Vertebrate Skeleton, 8vo, 1840, p. 171.

"The extent to which the resemblance, expressed by the term Unity of Organization,' may

species of plants and animals. Demaillet invoked the operation of the external influences or conditions of life, with consentaneous volitional efforts, in order to raise species in the scale, as the fish, e. g., into the bird. Buffon called in the same agency to lower the specics, by way of degeneration, as the bear, e. g., into the seal, and this outward influences the effects of increased into the whale.† Lamarck added to these or decreased use or action of parts. The Author of "Vestiges," availing himself of the ingenious illustration of a pre-ordained exception, occurring at remote intervals, to the ordinary course, derived by Babbage from the working of his calculating engine, threw out the suggestion of a like rare exception in the character of the offspring of a known species, and he cites the results of embryological studies, to show how such "monster," either by excess or defect, by arbe no monster in fact, but one of the prerest or prolongation of development, might ordained exceptions in the long series of natural operations, giving rise to the introduction of a new species. Owen applies the more recent discoveries of Parthenogenesis to the same mysterious problem. A polype, e. g., breaks up into a pile of medusa; "the indirect or direct action of the conditions of life" might tend to harden the integument and change the medusa into a star-fish. But he resists the seduction of possibilities, and governed by the extent of actual observation, says: "The first acquaintance with these marvels excited the hope that we were about to penetrate the mystery of the origin of species; but as far as observation has yet extended, the cycle of changes is definitely closed." ‡

Mr. Wallace calls attention to the "tre

be traced between the higher and lower organized animals, bears an inverse ratio to their approximation to maturity." (Owen, Lectures on Invertebrata, p. 645.)

Telliamed, ou Entretiens d'un Philosophe Indien avec un Missionaire François, Amsterdam, 8vo, 1748. Histoire Naturelle, etc., 4to, tom. XIV. 1766. Address to the British Association at Leeds,

1858, p. 27,

forcibly and truly expresses it, both species and genus; such are the elephant, rhinoceros, hippopotamus, giraffe, camel, lion, bear, and mole. † Palæontology has since re

mendous rate of increase in a few years from a single pair of birds producing two young ones each year, and this only four times in their life; in fifteen years such pair would have increased to nearly ten millions!"vealed the evidences of the true nature and The passenger-pigeon of the United States causes of the present seeming isolation of exemplifies such rate of increase, where con- some of these forms. genial food abounds. But, as a general rule, the animal population of a country is stationary, being kept down by a periodical deficiency of food, and other checks. Hence the struggle for existence; and the successful result of adapted organization and powers in a well-developed variety, which Mr. Darwin generalizes as "Natural Selection," and which Mr. Wallace † illustrates as follows:"An antelope with shorter or weaker legs must necessarily suffer more from the attacks of the feline carnivora; the passenger-pigeon with less powerful wings, would sooner or later be affected in its powers of procuring a regular supply of food." If, on the other hand, "any species should produce a variety having slightly increased powers of preserving existence, that variety must inevitably in time acquire a superiority in numbers." " During any change tending to render existence more difficult to a species, tasking its utmost powers to avoid complete extermination, those individuals forming the most feebly organized variety would suffer first; the same causes continuing the parent species would next suffer, would gradually diminish in numbers, and with a recurrence of similar unfavorable conditions, must soon become extinct. The superior variety would then alone remain,

and on a return to favorable circumstances

would rapidly increase in numbers and occupy the place of the extinct species and variety The variety would now have replaced the species of which it would be a more perfectly developed and a more highly organized form."§

Such evidences have been mainly operative with the later adopters and diffusers of Buffon's principle in the reduction of the number of primitive sources of existing species, and the contraction of the sphere of direct creative acts. Thus Lamarck ‡ reduces the primordial forms or prototypes of animals to two, viz. the worm (vers), and the monad (infusoires); the principles which in the course of illimited time operated, on his hypothesis, to produce the present groups of animals led from the vibrio, through the annelids, cirripeds, and molluscs to fishes, and there met the other developmental route by way of rotifers, polypes, radiaries, insects, arachnides, and crustacea. The class of fishes, deriving its several forms from combinations of transmuted squids and crabs, then proceeded through the well-defined vertebrate pattern up to man. With a philosophic consistency, wanting in his latest follower, Lamarck sums up: d'animaux commençant par deux branches où se trouvent les plus imparfaits, les premiers de chacune de ces branches ne reçoivent l'existence que par génération directe ou spontanée." §

"Cette série

exact ideas of the affinities and relationships Mr. Darwin, availing himself of the more of animal groups obtained by subsequent induction, says: "I believe that animals have descended from at most only four or five progenitors," [evidently meaning, or answerBuffon regarded varieties as particular al- ing to, the type forms of the four or five terations of species, as supporting and illus-"sub-kingdoms" in modern zoology], “and trating a most important principle-the mu- plants from an equal or lesser number." tability of species themselves. The so-called But if the means which produce varieties varieties of a species, species of a genus, genera of a family, etc., were, with him, so many evidences of the progressive amount or degrees of change which had been superinduced by time and generations upon a primordial type of animal. Applying this principle to the two hundred mammalian species of which he had given a history in his great work, he believed himself able to reduce them to a very small number of primitive stocks or families. Of these he enumerates fifteen besides which, Buffon specifies certain isolated forms, which represent, as he *Proceedings of the Linnæan Society, 1858, p.

55.

have operated "through the enormous species of time, within which species are changed," || the minor modifications which produce, under our brief scope of observation, so-called varieties, might well amount to differences equivalent to those now separating sub-kingdoms; and, accordingly, "analogy," Mr. Darwin logically admits, "would lead us one step further, namely, to the belief that all animals and plants have descended from some one prototype;" and summing up the conditions which all living things have

*"Quelques espèces isolées, qui, comme celle de l'homme, fassent en même temps espèce et genre."-Tom. cit. p. 335.

† Ib., p. 360.

Philosophie Zoologique, vol. ii. p. 463.
Ib., p. 463.

Vestiges of Creation, p. 231.

TOp. cit., p. 484.