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too often looked upon as something adventitious and superficial, something given to an animal not to be useful to itself, but solely to gratify man or even superior beings — to add to the beauty and ideal harmony of nature. If this were the case, then, it is evident that the colours of organised beings would be an exception to most other natural phenomena.

They would not be the product of general laws, or determined by ever-changing external conditions ; and we must give up all enquiry into their origin and causes, since (by the hypothesis) they are dependent on a Will whose motives must ever be unknown to us. But, strange to say, no sooner do we begin to examine and classify the colours of natural objects, than we find that they are intimately related to a variety of other phenomena, and are, like them, strictly subordinated to general laws. I have here attempted to elucidate some of these laws in the case of birds, and have shown how the mode of nidification has affected the colouring of the female sex in this group. I have before shown to how great an extent, and in how many ways, the need of protection has determined the colours of insects, and of some groups of reptiles and mammalia, and I would now call particular attention to the fact that the gay tints of flowers, so long supposed to be a convincing proof that colour has been bestowed for other purposes than the good of its possessor, have been shown by Mr. Darwin to follow the same great law of utility. Flowers do not often need protection, but very often

require the aid of insects to fertilize them, and maintain their reproductive powers in the greatest vigour. Their gay colours attract insects, as do also their sweet odours and honeyed secretions; and that this is the main function of colour in flowers is shown by the striking fact, that those flowers which can be perfectly fertilized by the wind, and do not need the aid of insects, rarely or never have gaily-coloured flowers.

This wide extension of the general principle of 'utility to the colours of such varied groups, both in

the animal and vegetable kingdoms, compels us to acknowledge that the “ reign of law” has been fairly traced into this stronghold of the advocates of special creation. And to those who oppose the explanation I have given of the facts adduced in this essay, I would again respectfully urge that they must grapple with the whole of the facts, not one or two of them only. It will be admitted that, on the theory of evolution and natural selection, a wide range of facts with regard to colour in nature have been co-ordinated and explained. Until at least an equally wide range of facts can be shown to be in harmony with any other theory, we can hardly be expected to abandon that which has already done such good service, and which has led to the discovery of so many interesting and unexpected harmonies among the most common (but hitherto most neglected and least understood), of the phenomena presented by organised beings.

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VIII.

CREATION BY LAW. AMONG the various criticisms that have appeared on Mr. Darwin's celebrated - Origin of Species,” there is, perhaps, none that will appeal to so large a number of well educated and intelligent persons, as that contained in the Duke of Argyll's 6 Reign of Law.” The noble author represents the feelings and expresses the ideas of that large class, who take a keen interest in the progress of Science in general, and especially that of Natural History, but have never themselves studied nature in detail, or acquired that personal knowledge of the structure of closely allied forms,—the wonderful gradations from species to species and from group to group, and the infinite variety of the phenomena of " variation ” in organic beings,which are absolutely necessary for a full appreciation of the facts and reasonings contained in Mr. Darwin's great work.

Nearly half of the Duke's book is devoted to an exposition of his idea of “ Creation by Law," and he expresses so clearly what are his difficulties and objections as regards the theory of “Natural Selection,” that I think it advisable that they should be fairly answered, and that his own views should be shown to lead to conclusions, as hard to accept as any which he imputes to Mr. Darwin.

The point on which the Duke of Argyll lays most stress, is, that proofs of Mind everywhere meet us in Nature, and are more especially manifest wherever we find “contrivance” or “beauty.” He maintains that this indicates the constant supervision and direct interference of the Creator, and cannot possibly be explained by the unassisted action of any combination of laws. Now, Mr. Darwin's work has for its main object, to show, that all the phenomena of living things—all their wonderful organs and complicated structures, their infinite variety of form, size, and colour, their intricate and involved relations to each other,-may have been produced by the action of a few general laws of the simplest kind, laws which are in most cases mere statements of admitted facts. The chief of these laws or facts are the following:

1. The Law of Multiplication in Geometrical Progression.—All organized beings have enormous powers of multiplication. Even man, who increases slower than all other animals, could under the most favourable circumstances double his numbers every fifteen years, or a hundred-fold in a century. Many animals and plants could increase their numbers from ten to a thousand-fold every year.

2. The Law of Limited Populations. The number of living individuals of each species in any country, or in the whole globe, is practically stationary ; whence it follows that the whole of this enormous increase must die off almost as fast as produced, except only those individuals for whom room is made by the death of parents. As a simple but striking example, take an oak forest. Every oak will drop annually thousands or millions of acorns, but till an old tree falls, not one of these millions can grow up into an oak. They must die at various stages of growth.

3. The Law of Heredity, or Likeness of Offspring to their Parents. This is a universal, but not an absolute law. All creatures resemble their parents in a high degree, and in the majority of cases very accurately; so that even individual peculiarities, of whatever kind, in the parents, are almost always transmitted to some of the offspring.

4. The Law of Variation. This is fully expressed by the lines :

“No being on this earthly ball,

Is like another, all in all.” Offspring resemble their parents very much, but not wholly-each being possesses its individuality. This 5 variation” itself varies in amount, but it is always present, not only in the whole being, but in every part of every being. Every organ, every character, every feeling is individual ; that is to say, varies from the same organ, character, or feeling in every other individual.

5. The Law of unceasing Change of Physical Conditions upon the Surface of the Earth.Geology shows us that this change has always gone on in times past, and we also know that it is now everywhere going on.

6. The Equilibrium or Harmony of Nature.—When a species is well adapted to the conditions which

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