the conditions of success, and that every cause of failure, well ascertained, is an encouragement to the repetition of the trial. Every practical physicist, therefore, was prepared to expect a certain number of instructive failures in the attempt to carry out the grandest philosophical experiment on record-the most stupendous which mortal mind ever ventured to propose to itself. Our surprise is, that the failures were so few, -the success so speedy. But the persevering and determined men who achieved this success, temporary as it has been, were animated by the spirit in which Lord Bacon tells us experimental philosophy should be entered upon :-"For there is no comparison," he writes, "between that which we may lose by not trying and by not succeeding; since by not trying we throw away the chance of an immense good, by not succeeding we only incur the loss of a little human labour."

On the 6th of August, 1858, the laying down of upwards of 2000 nautical miles of the telegraphic cord, connecting Newfoundland and Ireland, was successfully completed; and shortly after, a message of thirty-one words was transmitted in thirty-five minutes along the sinuosities of the submerged hills and valleys forming the bed of the great Atlantic. This first message ended by expressing-"GLORY TO GOD IN THE HIGHEST: ON EARTH PEACE, GOODWILL TOWARDS MEN." Never since the foundations of the world were laid could it be more truly said, "The depths of the sea praise Him!"

More remains to be done before the far-stretching, thought-bearing engine can be got into full working order; but the capital fact, viz., the practicability of bringing America into electrical communication with Europe has been demonstrated; consequently a like power of instantaneous interchange of thought between the civilized inhabitants of every part of the globe becomes only a question of time. The powers and benefits thence to ensue for the human race can be but dimly and inadequately foreseen. Some results stand out more prominently than others.

The investigator of natural laws manifests his success by the degree in which he elicits and substitutes latent natural force for manual labour in effecting his purpose. Sennacherib, as we see on the slabs from Nineveh, added the lever to traction in the transport of the colossal symbolic statues of his majesty; but the power by which he worked both mechanical adjustments was slaves stimulated by the stick. Hundreds of human beings were sacrificed in the operation. WATT achieved an equal effect by the scientific eduction and direction of the latent force contained in a few pounds of coal.

If this test be applied to the present state of the science of governing peoples, it would seem to show but little progress therein. The conscription committee of France for 1858 proposed a levy of 100,000 men, because less would not suffice to keep up the requisite army of 500,000 men; Europe being at peace. Even the United States of America have progressively increased their standing army to a present total of 17,000 men.

The probability of a further augmentation of the military force of the Federal Government, in reference to a possible rupture with the Mothercountry, must be greatly diminished by an ocean telegraph. And we may confidently hope that this and other applications of pure science will tend to abolish wars over the whole earth; so that men may come to look back upon the trial of battle between misunderstanding nations, as a sign of a past state of comparative barbarism; just as we look back from our present phase of civilization in England upon the old border-warfare.

Bacon, commenting on the History of the Works of Nature, as it presented itself to him, describes it as a chaos "of fables, antiquities, quotations, frivolous disputes, philology, ornaments, and table-talk." Since his day the chief steps, by which Natural History has advanced to the dignity of a science, are associated with the names of Ray, Linnæus, Jussieu, Buffon, and Cuvier.

By the two former the phenomena were digested and classified, according to artificial but conveniently applicable methods; of necessity the precursors of systems more expressive of the natural affinities of plants and animals. To perfect the natural system of plants has been the great aim of botanists since Jussieu. To obtain the same true insight into the relations of animals has stimulated the labours of zoologists since the writings of Cuvier. To that great man appertains the merit of having systematically pursued and applied anatomical researches to the discovery of the true system of distribution of the animal kingdom: nor, until the Cuvierian amount of zootomical science had been gained, could the value and importance of Aristotle's 'History of Animals' be appreciated. The Greek philosopher, in this department of science, had advanced far beyond his systematic depreciator, Bacon, who could not, in fact, in the then state of natural knowledge, comprehend his discoveries. Such was the low state of Zoology in the interval between Aristotle and Cuvier, that there is no similar instance, in the history of science, of the well-lit torch gradually growing dimmer and smouldering through so many generations and centuries before it was again fanned into brightness, and a clear view regained, both of the extent of ancient discovery, and of the true course to be pursued by modern research. Rapid and right has been the progress of Zoology since that resumption. Not only has the structure of the animal been investigated, even to the minute characteristics of each tissue, but the mode of formation of such constituents of organs, and of the organs themselves, has been pursued from the germ, bud, or egg, onward to the maturity and decay of the individual. To the observation of outward characters is now added that of inward organization and developmental change, and Zootomy, Histology, and Embryology combine their results in forming an adequate and lasting basis for the higher axioms and generalizations of Zoology properly so called.

Three principles, of the common ground of which we may ultimately obtain a clearer insight, are now recognized to have governed the construc1858.

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tion of animals:-unity of plan, vegetative repetition, and fitness for purpose. The last, alone, has of late been questioned: but, in reference to such structures as are exemplified by the flood-gates of the heart and the lens of the eye, I find my own powers of conception and expression such as to leave me no other mode of understanding myself, or of being intelligible to others, than by using the terms 'aim,' 'end,' 'purpose,' or 'design,' in regard to the relation of the first instanced structure to the course of the blood in the circulatory system; and of the second to the convergence of light in the act of vision.

The independent series of researches by which students of the Articulate animals have seen, in the organs performing the functions of jaws and limbs of varied powers, the same or homotypal elements of a series of like segments constituting the entire body, and by which students of the Vertebrate animals have been led to the conclusion that the maxillary, mandibular, nyoid, scapular, costal and pelvic arches, and their appendages sometimes forming limbs of varied powers, are also modified elements of a series of essentially similar vertebral segments, mutually corroborate their respective conclusions. It is not probable that a principle which is true for Articulata should be false for Vertebrata: the less probable, since the determination of homologous parts becomes the more possible and sure in the ratio of the perfection of the organization.

The last proposition may be tested by a study of any single set of organs with a view to determine their homologies.

Take, for instance, the teeth, or the organs properly so called, which are peculiar to the vertebrate animals. One cannot trace any particular tooth, as one may a bone, from Fish to Fish: they are too numerous and too uniform. In Reptiles we may point to the maxillary poison-tooth of a Rattlesnake as answering to that in a Cobra; the homological relations of the teeth being only predicable in a general way, as premaxillary, maxillary, mandibular, palatine, in the rest of that class. But when we come to the Mammalia, we find, save in a few inferior groups resembling fishes (e. g. Cetacea) or resembling reptiles (Bruta), that the teeth have such determinate characters, from relative position and development, as to enable the anatomist to trace each individual tooth from species to species, and indicate it, throughout that large proportion of the class which has been called 'diphyodont,' by a determinate name and symbol.

And here I would repeat, what I have elsewhere expressed, that each year's experience strengthens the conviction that the right and quick progress of the knowledge of animal structures, and of the axioms deducible therefrom, will be mainly influenced by the determination of homologies and by the concomitant power of condensing the propositions relating to homologized parts, by means of definite single substantive names, and their equivalent signs or symbols.

In my work on the 'Archetype of the Skeleton,' I have denoted most of the bones by numerals, which, when adopted, may take the place of names; for then all propositions respecting the centrum of the occipital vertebra might be predicated of '1' as intelligibly as of basioccipital.' The name appears to be now generally accepted, and why not the symbol? The symbols of the teeth are as definite as those of the bones; and, in the absence of single names, more useful, since they render unnecessary the repetition of the compound definitions; they harmonize conflicting synonyms, serve as a universal language, and express the writer's meaning in the fewest and clearest terms. The entomologist has realized the advantage of signs, such as ♂, &, &c. for male, female, neuter, and the like; and the time is come when the anatomist may avail himself of this powerful instrument of thought, instruction, and discovery, from which the chemist, the astronomer, and the mathematician have obtained such important results.

To William Sharp Macleay, author of the 'Horæ Entomologicæ,' belongs the merit of first clearly defining and exemplifying, in regard to the similarities observable between different animals, the distinction between those that indicate 'affinity' and those that indicate 'analogy' or representation. This distinction has been well illustrated by Vigors in the class of Birds, and has been ably discussed by Swainson in reference to other classes of animals.

'Affinity,' as first defined by Macleay in contradistinction from 'analogy,' signifies the relationship which one animal bears to another in its structure, and is the closer as the similarity of structure is greater. Swainson illustrates this idea by comparing a goatsucker with a swallow and with a bat: with the one its relation is intimate, with the other remote: the goatsucker has affinity with the swallow, analogy to the bat.

But the idea of the foregoing intimate relation of entire animals, called 'affinity,' is different from the idea of the answerable relation of parts of animals called 'homology.' Animals, however intimately 'affined,' are never the same in the sense in which homologous parts are so esteemed: they could never be called by the same name, in the way or sense in which a bone, for example, of the fore-limb, is called 'humerus' in the goatsucker, swallow, and bat.

There is, indeed, a sameness in the idea of 'analogy,' as applied by the Zoologist to animals, and by the Anatomist to their parts. The goatsucker is related by analogy to a bat, because, as Mr. Swainson remarks, " it flies at the same hour of the day, and feeds in the same manner; " and the membranous wing of the bat is analogous to the membranous parachute of the dragon, because it serves to sustain the body in the air. That is to say, 'function' a similar relationship to a tertium quid-in the above instance air, - is the groundwork for predicating analogies in regard to parts as well as wholes; more especially when, as in the case of the wings of the dragon and bat, they are not homologous parts.

The study of homologous parts in a single system of organs-the bones -has mainly led to the recognition of the plan or archetype of the highest

primary group of animals, the Vertebrata. The next step of importance will be to determine the homologous parts of the nervous system, of the muscular system, of the respiratory and vascular system, and of the digestive, secretory, and generative organs in the same primary group or province. I think it of more importance to settle the homologies of the parts of a group of animals constructed on the same general plan, than to speculate on such relations of parts in animals constructed on demonstratively distinct plans of organization. What has been effected and recommended, in regard to homologous parts in the Vertebrata, should be followed out in the Articulata and Mollusca.

In regard to the constituents of the crust or outer skeleton and its appendages in the Articulata, homological relations have been studied and determined to a praiseworthy extent, throughout that province.

The same study is making progress in the Mollusca; but the grounds for determining special homologies are less sure in this subkingdom. The vegetative functions here predominate; and just as the organs of these functions are less satisfactory subjects of homological determination than those of the animal functions in the Vertebrate province, so the Molluscous province is a less favourable field for homological demonstrations than either the Articulate or Vertebrate provinces, in which the animal functions predominate over the vegetative.

So far as homologies can be determined, within the limits in which such determination can be most satisfactorily carried out, the foundation will be securely laid for a superstructure of higher generalizations in regard to parts homological or answerable throughout the animal kingdom generally.

The present state of homology in regard to the Articulata has sufficed to demonstrate that the segment of the crust is not a hollow expanded homologue of the segment of the endoskeleton of a vertebrate. There is as little homology between the parts and appendages of the segments of the Vertebrate and Articulate skeletons respectively. The parts called mandibles, maxillæ, arms, legs, wings, fins, in Insects and Crustaceans, are only 'analogous' to the parts so called in Vertebrates.

To express finitely the clear deideas now possessed of their essential distinction, will require a distinct nomenclature. The same remark is applicable to other systems of organs. The so-called 'lungs' of the spider are analogous to, not homologous with, our 'lungs:' the tracheæ of insects are not homologous with the bird's trachea and its ramifications: the gills of the lobster are not the homologous parts of the gills of fishes. No comparative anatomist now supposes that the heart of the lobster is homologous with that of a fish; or either of these organs with the heart of a snail. The name in each group is simply expressive of similarity of function, and of connexions limited by and solely related to such function, as of the heart with a vein and an artery. A most extensive field of reform is becoming open to the homologist in that which is essential to the exactitude of his science-a no