to natural science, a cumbrous nomenclature, by devising an admirable plan of naming.* He divided all living creatures into two great series of successively subordinate groups (one series of animals, the other of plants), the animal and vegetable kingdoms. He defined his various groups of either kingdom by certain resemblances and differences in form and structure, and though his arrangement of plants has been mainly discarded, and his arrangement of animals much changed, and further subdivided, yet the principles he introduced and many parts of his actual classification have been and will be maintained. For his reform in nomenclature above referred to we owe him hearty thanks. Till then, the mode of naming animals and plants was at once cumbrous and little instructive, a descriptive phraset being often employed to designate a particular kind.

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The system of naming which Linnæus devised was a binomial system which is now universally adopted. By it every kind of living creature bears a name made up of two words. These (like the family and Christian names of a man) indicate two things. The word which comes first indicates to which smaller group or "genus" the designated animal belongs. The second word indicates which kind or species" (out of the few or many kinds of which such smallest group or genus" may be composed) of the genus the designated animal may be. Thus, for example, the name borne by the sheep is Ovis ariesthat is to say, it is the kind aries of the group, or genus, ovis. The word pointing out the group to which the animal is referred is termed the generic" name; the word pointing out the kind is called the specific" name-Ovis being the name of the genus and aries being pecu

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* Promulgated by him in the tenth edition of his Systema Natura, published at Stockholm in 1758.

Thus, for example, one kind of bat was called by Seba, "canis volans ternatanus orientalis," and a kingfisher is termed "todus viridis pectore rubro rostro recto."

It is not improbable that Linnæus was influenced in this reform by the then recent introduction of family names into Sweden.

His father was the first of his race to take one, and he chose the name Linnæus as his sur

name.

liar to the species. This great reform has been of very great benefit to the study of natural history.

As has been already remarked, Linnæus's classification of animals and his classification of plants have not shared the same fate. The former has been modified and enlarged, the latter has been discarded. For this there has been a valid reason. Classifications may be of many sorts. We may classify any one given set of objects in a variety of ways according to the way we choose to consider them.

But there are two fundamental differences with respect to classification. An arrangement may be intended merely for convenient reference, or it may be intended to group the creatures classified according to their real affinities. A classification intended merely for conve nient reference may be made to depend upon characters arbitrarily chosen and easily seen, and which may stand alone and not coincide with a number of other distinctions. For example, when beasts were arranged in a group of "quadrupeds" (having for their common character the possession of four limbs), such an arrangement excluded from the group whales and porpoises (which are really most closely related to other beasts), while it included lizards and frogs, which are of natures very distinct both from beasts and from one another. But a classification may be made to rest on distinctive characters, which coincide with a great number of other distinctions, and so lead to the association of creatures which are really alike, and which will be found to present a greater and greater number of common characters the more thoroughly they are examined. A system of classification of this latter kind is called a "natural system," because it represents and leads us directly to understand the inter-relations of different creatures as they really exist in Nature.

A natural system has also other advantages; it not only serves as a memoria technica as well as a mere artificial system may do, but it also serves (since it must become modified in details as our knowledge increases) as a register of the knowledge existing at the time of its promulgation, and also as a help to discovery; for since by such a system

these animals are grouped together by a great number of common characters, it leads us (when any new animal or plant comes under our notice) to seek for certain phenomena when once we have observed others with which such expected phenomena are, according to our supposed classification, associated. Thus a natural system serves to guide us in the path of investigation. Now Linnæus's classification of animals was, to a considerable extent, natural, and therefore has, to a considerable extent, persisted. But his classification of plants reposed upon variations in the more internal (reproductive) parts of flowers (stamens and pistil) as other anterior and less celebrated systems had reposed on the form of the colored parts of flowers,* or on such parts together with their green envelope † (or calyx), or only upon the form of, the fruit. The genius of Linnæus was not, however, blind to the imperfection of his own classification, for he himself proclaimed § that a natural system was the one great desideratum of botanical science.

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The desideratum was supplied at a memorable era. In 1789 Antony Jussieu inaugurated this botanical revolution by publishing his Genera Plantarum, and therein that natural system of classification of plants which has since (with but small modification) been generally adopted.

The great French naturalist, Buffon, did not live to witness the publication of the last-mentioned work. Had he lived to study it, he might have gained a truer insight into the importance of biological classification, and have endeavored to improve on Linnæus's system, instead of contenting himself with criticising and despising it. In spite of his defective appreciation of the importance of a good arrangement and nomenclature, Buffon greatly aided the progress of Natural History, not only by his

eloquent descriptions of the animal world and his zeal for the discovery of new forms, but still more by his suggestive speculations. Amongst these latter may be mentioned his theories of the earth, of the process of generation, his view as to the relations between the animals of the old world and of the new, and, most striking of all, his enunciation of the probability that species had been transformed and modified. In spite of much that was erroneous in his ideas his suggestions have borne good fruit.

Almost simultaneously with the promulgation of a natural system of plants, George Cuvier was laboring to complete a zoological task similar to the botanical one effected by Jussieu. Cuvier, availing himself of the work of Linnæus, elaborated his Règne Animal,* and carried zoology by his untiring researches and encyclopædic knowledge to the highest perfection possible in his day. He did this not only as regards living kinds, but also with respect to extinct species, † which he, for the first time, restored in imagination, giving figures of what were their probable external forms. As then, Linnæus, by his nomenclature and system of zoological classification, made one important step in the progress of modern biology, so a second step was effected by the arrangement of all known animals and plants, in a truly natural system, by Jussieu and Cuvier.

A further advance was at the same time rapidly approaching, for simultaneously with the perfecting of the knowledge of structural anatomy as so many matters of fact, a movement of deep significance was stirring the minds of men in Germany-a movement which resulted in the birth of what has been called philosophical anatomy." With this, the names of Oken, Goethe, Geoffrey St. Hilaire, and Owen are, with others, indissolubly associated. According to this "philosophical anatomy," it is pos

sible for men, from a judicious study of living creatures, to gather a conception of certain formative "ideas" which have governed the production of all animals and vegetables. These ideas were conceived as either ideas in God or as ideas existing somehow in a Pantheistic universe. The "ideas" were supposed to be nowhere actually realized in the world around us, but to be approximated to in various degrees and ways by the forms of living creatures. The naturalists of this school triumphantly refuted the old notion that all the structures of living beings were sufficiently explained by their wants. Thus they pointed out the absurdity of supposing that the bones of the embryo's skull originate in a much subdivided condition, in order to facilitate parturition, when the skulls of young birds, which are hatched from eggs, also arise in a similarly subdivided condition. Many other similar popular instances of final causation in animal structure they similarly explained away. Some of the views put forth by leaders of the movement-as, for example, by Oken were extremely fantastic, and were connected with the philosophic dreams of Hegel and of Schelling. Other of their views, however, were both significant and fruitful, for they directed special attention to such facts as the presence in some animals of rudimentary structures. Rudimentary structures are minute structures which some animals have (e.g., the wing bones of the New Zealand Apteryx), and which are miniature representatives of parts which are of large size and of great use in other animals. Other such significant facts are those of animal development, as when Goethe discovered in the skull of the human fœtus a separate bone of the jaw, which is no longer separate even at birth, and which, before his time, was supposed only to exist in lower animals.

*

Thus fresh interest was lent to a most important study, which may be said to have been initiated by Caspar Friedrich Wolff, which was further developed by Pander and Döllinger, and carried to

*Thus he represented the teeth as being the fingers and toes of the head.

In 1859 in a dissertation as Doctor, at Halle, he put forward his Theoria Generationis, embodying very many new and accurate investigations.

"Historia Metamorphoseos," 1817.

*

great perfection by Van Baer and Rathke. The study in question was that of animal development-that is, a study of the phases which different animals go through in advancing from the egg to their adult condition. It had of course been long known to all that such animals as the frog and the butterfly undergo great changes during this process, but the study of development revealed to us the strange fact that animals generally, before birth, also undergo great changes, during which each such creature transitorily resembles the permanent condition of other creatures of an inferior grade of organisation.

Philosophical anatomy and the study of development were both highly provocative of research, tending as they did to destroy conceptions on which men's minds had previously reposed, without at the same time substituting any other satisfactory and enduring mental restingplace. They thus prepared the way for that great modern advance-the conception of organic evolution, or the development from time to time of new kinds of animals and plants by ordinary natural processes-a conception the promulgation and general acceptance of which constitutes another great epoch in the cultivation of Natural History.

But as the Linnæan movement was despised by Buffon, so was philosophical anatomy despised by Cuvier. Each of these great naturalists seems to have been so attracted by the brilliance of such faces of the many faceted form of truth as they clearly saw, that they became more or less blinded to other of its faces, in themselves no less brilliant and captivating.

But if philosophical anatomy and the theory of Wolff had to encounter strenuous opposition, still greater was the opposition which met the efforts of those who first asserted organic and specific evolution.

Before the theory of evolution was distinctly enunciated it had its prophetic precursors, even as far back as the days of Aristotle. In modern times, Buffon, as has been already said, threw out suggestions concerning the transformation of species, and Goethe, Geoffrey St.

Hilaire, and Dr. Erasmus Darwin also entertained similar views. But it was not until the beginning of the nineteenth century that the doctrine of evolution was (in modern times) unequivocally put forth. It was so put forth by Lamarck* in the year 1802. He declared that all existing animals had been derived from antecedent forms according to an innate law of progression, the action of which had been modified by habit, by cross-breeding, and by the influence of climatic and other surrounding conditions. His views were accepted by few, and encountered much ridicule; but the gradual modifications of opinion which were being brought about by philosophical anatomy and the study of development prepared the way for his more happy successors. After a considerable interval he was followed by Alfred Wallace and Charles Darwin, who attributed the origin of new species to the occurrence and parental transmission to offspring of indefinite minute variations -no two individuals being ever absolutely alike.

Such variations they conceived as taking place in all directions, but as being reduced to certain lines by the destructive agencies of Nature acting upon creatures placed in circumstances of severe competition, owing to the tendency of every kind of organism to increase in a geometrical ratio. This destructive action together with its result was termed by these authors" Natural Selection," but the whole process has been more aptly designated by the phrase," the survival of the fittest.'

The doctrine of evolution, however, has been accepted and advocated by other writers, who deny that "Natural Selection" can be the cause of the origin of species. They say that such origin must be due to whatever produces individual variation, and ultimately to inherent capacities in the organisms them

* In his "Researches on the Organization of the Living Bodies" (1802); in his "Philosophie Zoologique" (1809); and also in the introduction to his "Hist. Nat. des Animaux sans Vertebres" (1815).

Journal of Linnean Society, vol. iii., July Ist, 1858; and "Natural Selection." Macmillan. 1871.

Journal of Linnean Society, vol. iii., July Ist, 1858; and "The Origin of Species by Means of Natural Selection." John Murray. 1859.

selves. Thus Owen * has declared that derivation holds that every species changes in time, by virtue of inherent tendencies thereto;" and Theophilus Parsons, † of Harvard University, in 1860, put forth a similar view. In this country the same theory was independently put forward and advocated at much length in 1870 by the author of the present paper. In the work referred to, the objections to Natural Selection" were fully gone into,§ and the theory maintained that external stimuli so act on internal predisposing tendencies as to determine by direct seminal modification the evolution of new specific forms.

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We may then conceive the evolution of new specific forms to have been brought about in one or other of the six following ways. The change may have been due :

(1.) Entirely to the action of surrounding agencies upon organisms which have merely a passive capacity for being indefinitely varied in all directions, but which have no positive inherent tendencies to vary, whether definitely or indefinitely.

(2.) Entirely to innate tendencies in

each organism to vary in certain definite directions. (3.) Partly to innate tendencies to

vary indefinitely in all directions, and partly to limiting tendencies of surrounding conditions, which check variations, save in directions which happen accidentally to be favorable to the organisms which vary. (4.) Partly to innate tendencies to vary indefinitely in all directions, and partly to external influences which not only limit but actively stimulate and promote variation.

(5.) Partly to tendencies inherent in organisms, to vary definitely in certain directions, and partly

to external influences acting only by restriction and limitation on variation.

(6.) Partly to innate tendencies to vary definitely in certain directions, and partly to external influences which, in some respects, act restrictively, and in other respects act as a stimulus to variation.

It is this last hypothesis which appears to have the balance of evidence in its favor.

But whatever view may be accepted as to the mode of evolution, a belief in the fact of evolution has given an impulse to natural science the effect of which can hardly be over-estimated. By this belief the sciences which relate to life have been all more or less modified, for light has been thrown by it on many curious facts concerning the geographical and geological distribution of animals and plants. The presence of apparently useless structures—such as the wing of the Apteryx (before referred to) or the fœtal teeth of whales which never cut the gum-become explicable as the diminished representatives of large and useful structures present in their more or less remote ancestors.

The curious likenesses which underlie superficial differences between animals become also explicable through "evolution."

That the skeleton of the arm of man, the wing of the bat, the paddle of the whale, and the fore-leg of the horse should each be formed on the same type is thus easily to be understood. The butterfly and the shrimp, different as they are in appearance and mode of life, are yet constructed on one common

plan, of which they constitute diverging manifestations. No à priori reason is conceivable why such similarities should be necessary, but they are easily explicable if the animals in question are the modified descendants of some ancient common ancestor. We here, then, see an explanation-possibly complete-of the theories of philosophical anatomy. That curious series of metamorphoses which constitutes each animal's development, as recently explained, also receives a new explanation if we may regard such changes as an abbreviated record or history of the actual transformation each animal's ancestors may have undergone. Finally, by evolution we can understand the singularly complex resemblances borne by every adult animal and plant to a certain number of other animals and plants. other animals and plants. It is through these resemblances alone that the received systems of classification of plants and animals have been possible; and such classifications viewed in the light of evolution assume the form of genealogical trees of animal and vegetable descent. We have thus a number of facts and laws of the most varied kind upon which evolution throws a new light, and serves to more or less clearly explain. Evidently, then, with the acceptance of the theory of evolution, the natural history of animals and plants needs to be rewritten from the standpoint thus gained. And though there is no finality in science, yet there is much reason to suppose that a long period will elapse before any new modification of biological science occurs as great as that which has been and is being effected through the theory in question. -Contemporary Review.

THE philosopher Epictetus, who had a school at Nicopolis in Epirus at the end of the first century of our era, thus apostrophizes a young gentleman whom he supposes to be applying to him for education :

* Address delivered to the Eton Literary

Society.

"Young sir, at home you have been. at fisticuffs with the man-servant, you have turned the house upside-down, you have been a nuisance to the neighbors; and do you come here with the composed face of a sage, and mean to sit in judgment upon the lesson, and to criticise my want of point? You have en