not for many years been materially raised, although unlimited wealth and energy are expended in the attempt. This is held to prove that there are definite limits to variation in any special direction, and that we have no reason to suppose that mere time, and the selective process being carried on by natural law, could make any material difference. But the writer does not perceive that this argument fails to meet the real question, which is, not whether indefinite and unlimited change in any or all directions is possible, but whether such differences as do occur in nature could have been produced by the accumulation of variations by selection. In the matter of speed a limit of a definite kind as regards land animals does exist in nature. All the swiftest animals -deer, antelopes, hares, foxes, lions, leopards, horses, zebras, and many others, have reached very nearly the same degree of speed. Although the swiftest of each must have been for ages preserved, and the slowest must have perished, we have no reason to believe there is any advance of speed. The possible limits under existing conditions, and perhaps under possible terrestrial conditions, has been long ago reached. In cases, however, where this limit had not been so nearly reached as in the horse, we have been enabled to make a more marked advance and to produce a greater difference of form. The wild dog is an animal that hunts much in company, and trusts more to endurance than to speed. Man has produced the greyhound, which differs much more from the wolf or the dingo than the racer does from the wild Arabian.

Again, it is objected that the Pouter or the Fan-tail pigeon cannot be further developed in the same direction. Variation seems to have reached its limits in these birds. But so it has in nature. The Fan-tail has not only more tail feathers than any of the three hundred and forty existing species of pigeons, but more than any of the eight thousand known species of birds. There is, of course, some limit to the number of feathers of which a tail useful for flight can consist, and in the Fan-tail we have probably reached that limit. Many birds have the oesophagus or the skin of the neck more or less dilatable, but in no known bird is it so dilatable as in the Pouter pigeon. Here again the possible limit, compatible with a healthy existence, has probably been reached. In like manner the differences in the size and form of the beak in the various breeds of the domestic Pigeon, is greater than that between the extreme forms of beak in the various genera and subfamilies of the whole Pigeon tribe. From these facts, and many others of the same nature, we may fairly infer, that if rigid selection were applied to any organ, we could in a comparatively short time produce a much greater amount of change than that which occurs between species and species in a state of nature, since the differences which we do produce are often comparable with those which exist

between distinct genera or distinct families. The facts adduced by the writer of this article, of the definite limits to variability in certain directions in domesticated animals, are no objection whatever to the view that all the modifications which exist in nature have been produced by the accumulation by natural selection of small and useful variations, since those very modifications have equally definite and very similar limits.

To another of this writer's objections-that by Professor Thomson's calculations the sun can only have existed in a solid state 500 millions of years, and that therefore time would not suffice for the slow process of development of all living organismsit is hardly necessary to reply, as it cannot be seriously contended, either that this calculation has any claims to even approximate accuracy, or that the process of change and development may not have been sufficiently rapid to have occurred within that period. His objection to the Classification argument is, however, more plausible. The uncertainty of opinion among Naturalists as to which are species and which varieties, is one of Mr. Darwin's very strong arguments that these two names cannot belong to things quite distinct in nature and origin. The Reviewer says that this argument is of no weight, because the works of man present exactly the same phenomena, and he instances patent inventions, and the excessive difficulty of determining whether they are new or old. I accept the analogy, and maintain that it is all in favour of Mr. Darwin's views. For are not all inventions of the same kind directly affiliated to a common ancestor. Are not improved Steam Engines or Clocks the lineal descendants of some existing Steam Engine or Clock? Is there ever a new Creation in Art or Science any more than in Nature? Did ever patentee absolutely originate any complete and entire invention, no portion of which was derived from anything that had been made or described before? It is therefore clear that the difficulty of distinguishing the various classes of inventions which claim to be new is of the same nature as the difficulty of distinguishing varieties and species, because neither are absolute new creations, but both are alike descendants of pre-existing forms, from which and from each other they differ by varying and often imperceptible degrees. It appears then, that however plausible this writer's objections may seem, whenever he descends from generalities to any specific statement, his supposed difficulties turn out to be in reality strongly confirmatory of Mr. Darwin's view.

I cannot conclude this paper without expressing my admiration of the manner in which many subjects are treated in the "Reign of Law." With the definition and limitation of the term "Supernatural," I cordially agree. The exposition of the mechanism of flight is in every respect admirable; and the views on the Political

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and Social aspects of the Free Labour question are calculated to do much good, and to draw attention to a subject of the highest importance. The want of equal success in treating the question of the Origin of Species, is no doubt due to the excessively varied and complex nature of the phenomena presented by organized beings. Fully to grasp what is involved in that question demands a knowledge of details, which it requires years of study to amass; and without such knowledge the acutest and most comprehensive intellect will not suffice to solve so intricate a problem.

II. INTERNATIONAL EXHIBITIONS.

By FRED. CHAS. DANVERS, M.S.E.

Ar the close of another grand International Exhibition we may well pause for a while and consider how far these great displays of the works of industry have fulfilled the objects for which they were first established. The thirteenth Paris Industrial Exhibition, and the second International collection of works of art and industry which has been held in that city, is now within a few days of its termination; and we may, therefore, for all practical purposes, speak of it as a thing of the past. Whatever articles of exhibition it may have contained that were considered especially deserving of remark have long since been reported on, and the Exhibitors have been awarded such prizes as the respective juries have thought fit to recommend. The building will yet remain open for a short time longer, and then the work of removal and demolition will speedily commence.

Before making any special allusion to the Paris Exhibition, it is our present intention to take a hasty glance at the origin and growth of Exhibitions generally, and the measures which preceded the first International Exhibition. We are indebted for much of our information on this subject to a Report on the Paris Exhibition, drawn up for the Society of Arts by M. Digby Wyatt, Esq., in 1849; and, with reference to Exhibitions in England, to the Official Catalogue of the International Exhibition of London, published in 1862.

Industrial Exhibitions in their early youth may have been content with a pedlar's pack, the travelling show-van, or a booth at a fair; but as soon as they gave up their gipsy life they began as national displays. It was long before the growing free-trade spirit of the age allowed them to become international, although museums did occasionally dabble in the products of foreign industry, and a catalogue of curiosities exhibited at the public theatre of Leyden, in 1699, gives an amusing account of one of these early Exhibitions.