condition, each stamen is seen to consist of a stalk (the filament) (f), to which another and movable stalk (the connective) (m), bearing an anther-cell at each end, is attached. Only one of these anthercells (a') is fully developed in each stamen. The connective (m),

like a swing-bar, can be pushed backwards on its axis so as to bring the fully-developed or upper anther-cell (a') to a horizontal position (Fig. 231, C). Such a result is actually brought about by the bee. Thrusting its head into the flower in the search for nectar, the insect pushes before it the lower end of the swing-bar, and thus brings the upper end of the bar with its ripe anther (a) in contact with its back (Fig. 232, A). This latter region is thus dusted with pollen, and when the insect flies to another. Salvia flower in which the pistil is ripe, the stigma (Fig. 232, B st), as we have seen, will in due course receive the pollen through

contact with the back of the bee.

A single paragraph only is permissible regarding the curious details connected with the fertilisation of the Orchids, which possess

flowers (Fig. 238) of markedly irregular shape. The lip (77) in such a flower as Orchis mascula, a common British species, is very broad; whilst the nectary to which bees desire admittance is extremely long (Fig. 240, n). The pollen forms two club-shaped masses (Figs. 239,

240 a), each adherent to a disc (Fig. 221, d), which in turn lies within the rostellum or cup (r). When touched, the rostellum breaks across, and thus allows the two glutinous discs (12, d) to become exposed. When a bee visits this peculiar flower, it pushes its proboscis into the nectary (n) for the sake of the honey contained therein. At the same time, the insect comes in contact with the discs of the pollen-masses (Fig. 239), these masses becoming adherent to the insect's head. A pencil pushed into an orchis detaches the pollen-masses after the fashion of the insect's unconscious act. At first, the pollen-masses remain erect like two abnormal horns on the insect's head; but gradually they assume a horizontal position, so that the insect cannot fail to charge the next orchid-pistil it enters with the pollen-masses. The stigma, or top of the pistil (Fig. 238, st, st), is so placed in these flowers that pollen-masses borne on a bee's head are certain to strike this surface, and thus fertilise the contents of the ovary. It is probable that as each pollen-mass consists of several packets of pollen-grains, one mass may contain material enough to fertilise several flowers; each stigma, through its viscid surface, detaching sufficient pollen from the mass for its fertilisation. The admirable adaptation of flower to insect and insect to flower, thus witnessed, is in no detail better exemplified than in the fact that the pollen-mass at first retains a vertical and then assumes a horizontal position in the insect's head. So long as the pollen-mass is vertical, fertilisation is impossible; and hence the vertical position persists so long as the bee is engaged in visiting the flowers of the plant from which it has derived pollenmasses. Thus self-fertilisation is prevented; so that, as Sir Joseph Hooker puts it, by the time the horizontal position of the pollenmass is assumed, "the bee has visited all the flowers of the plant from which it took the pollen, and has gone to another plant."

To enter into further illustration of the contrivances through which the fertilisation of flowers is secured would be to encroach on the province of the technical and practical botanist. Such details are "writ large" in the pages of every botanical text-book. In the works of Mr. Darwin-and especially in the "Fertilisation of Orchids"-the reader anxious for further details may find a perfect encyclopædia of facts constituting a veritable romance of botanical science. It, however, remains to us in the present instance to point out the plain meaning of these virtually marvellous adaptations of the plant-world to the work of cross-fertilisation, and to note, as far as possible, the bearing of such a study upon the order of nature regarded as a harmonious whole. It is a perfectly legitimate supposition that if cross-fertilisation forms, as we have seen, such a prominent feature of plant-life, that life must, in some very plain and obvious fashion, benefit therefrom. And further, as plant-life is but

a part of organic nature, we may feel perfectly justified in supposing that the conditions and results which cross-fertilisation tends to evoke and produce, will harmonise in their tendency and direction with the course of events through which the living universe has been and is being moulded, developed, and evolved.

To the question, "Why does cross-fertilisation appear to be favoured by nature over self-fertilisation?" a plain reply is at hand in a comparison of the results which accrue from each of these processes. Mr. Darwin's laborious researches on the comparative fertility of various species of plants when self-fertilised and crossfertilised, supply an answer to the foregoing question, by showing that in every respect the cross-fertilised flowers yield more seeds, and give rise to a stronger and more numerous progeny than the selffertilised. The reader who consults Mr. Darwin's "Forms of Flowers" will find himself supplied with ample data in proof of the advantages of cross-fertilisation. In the primrose, for instance, when short-styled and long-styled flowers were crossed in what Darwin calls "legitimate union," the result was invariably to produce a larger number of seeds than when each form was fertilised by its own pollen. Out of 12 long-styled primroses fertilised by short-styled pollen, 11 good capsules (or ripe pistils) were produced, with an average of 669 seeds per capsule; whilst 21 long-styled flowers, fertilised by long-styled pollen, produced only 14 capsules, with an average of 52 2 seeds per capsule. The cowslip gave a similar result; and the tendency towards greater vigour of offspring when crossfertilisation is employed, appears to be of the most general kind. In some plants, indeed, cross-fertilisation is absolutely essential for the mere continuance of the race; so that this method of seed-production is not merely accidental or advantageous, but absolutely necessary for the continuance of the race. Most of the orchids illustrate this state of matters. The presence of humblebees is well-nigh an absolute necessity for the continuance of the heartsease (Viola tricolor); and the well-known case of the clovers may be cited as highly characteristic of the benefits developed through crossfertilisation. Twenty heads of Dutch clover, protected by Darwin from bees, yielded no seeds: whilst twenty heads growing exposed as in a state of nature, yielded 2,290 seeds. One hundred heads of red clover protected from bees were absolutely sterile ; a second hundred exposed yielded 2,700 seeds. The scientific demonstration of the interdependence of living beings becomes in this fashion perfectly clear. Carried out to its ultimate results, such demonstration becomes sufficiently startling. British brain and sinew depend (according to a foreign estimate) on home-fed beef; whilst the quality of that nutriment is said to be dependent upon the clover on which the ox subsists. But clover owes its continuance to humblebees ;

humblebees in turn are killed by field-mice, whilst cats extirpate the rodents. As old maids conserve the feline race, it is alleged that the continuance of the British intellect is dependent upon such conservation-so that a scientific justification of spinsterhood is thus rendered possible.

Sprengel laid down the axiom, already mentioned, that "Nature does not wish any complete flower to be self-fertilised." Darwin in turn improves upon this dictum in his assertion that "Nature abhors perpetual self-fertilisation." That "cross-fertilisation is generally beneficial, and self-fertilisation injurious," is thus a stable result of botanical investigation. This result may not enable us fully to comprehend that "law within the law" which regulates the well-being of the plant-world; but it may at least lead us plainly enough to a nearer fact of life-namely, that there exists in nature an innate tendency to variation and change, and that by furthering the fullest possible development of seeds, as well as by the crossfertilising of plants, there is being illustrated that tendency to evolve new varieties and species on the existence of which the very idea and possibility of evolution depends. The tendency to produce a more numerous offspring gives naturally a larger number of individuals for the exhibition and operation of the laws of variation. The process of cross-fertilisation itself produces another tendency to variation; and as such variation is the "key-note" of evolution, it is more than interesting to find the conditions of plant-life in such a marked manner contributing to the differentiation of the species.

The whole array of features embraced in a study of flower-fertilisation forms simply a mass of evidence that the production of new races and varieties, and, through these, of new species, is part and parcel of nature's constitution. On any other supposition, the extraordinary array of contrivances favouring cross-fertilisation and the initiation of variations, is meaningless and utterly inexplicable. The facts of fertilisation, like the stages of development, present us with unimpeachable evidence in favour of the evolution of new races by the modification of the old. Even if a fact here or a detail there may seem to weigh against the theory of development, it must be borne in mind, firstly, that defects and gaps in our knowledge are still realities of biological science; and, secondly, that the general-and in this case the immensely overwhelming-probability of nature's and life's methods testifies to evolution as the true way of creation. Mr. Darwin succinctly enough says, that his experiments on intercrossing show that "with animals and plants a cross between different varieties, or between individuals of the same variety but of another strain, give vigour and fertility to the offspring; and, on the other hand, that close interbreeding diminishes vigour and fertility." And he also adds that such facts" alone incline me to believe that it is a general law

of nature that no organic being fertilises itself for a perpetuity of generations; but that a cross with another individual is occasionally -perhaps at long intervals of time-indispensable." Remarking the strange feature of the stamens and pistil of most flowers being placed closed together," as if for the very purpose of self-fertilisation," and yet being "mutually useless to each other," Mr. Darwin says, "How simply are these facts explained on the view of an occasional cross with a distinct individual being advantageous or indispensable!" Thus, from the common ground that cross-fertilisation effects the greatest good in nature-namely, the efficient increase of the racewe may find many roads and ways for the recognition of further effects of such action in favouring the operation of the conditions that increase the species by variation and modification. The full bearing of the subject may not be completely investigated for years to come. Sufficient, however, is our present recognition of the fact that in the work of flower-fertilisation lie the beginnings of those activities and processes which herald now, as of yore, not merely the increase, but the variation of species and the evolution of new forms of plants.

Certain matters bearing the same relation to our present subject that the inevitable moral bears to the fable-albeit that they may perchance be regarded as of somewhat superfluous nature-may fitly be touched upon in closing this paper. Our notions of special ends, aims, and contrivances in nature may in one way be enlarged by the considerations which the phenomena of flower-fertilisation present to notice. Under the operation of laws and conditions most of which are as yet beyond our ken, we see insect acting upon flower, and flower in turn reacting upon insect, until the interdependence in some cases proceeds so far that the extinction of the insect means the disappearance of the flower. But, whilst viewing the beauty of form and hue exhibited in the plant-world as wrought out by laws of development, and as accessory, or even primary, conditions in the evolution of living beings, the new and higher aspects of the subject bid us regard floral beauty as subserving other and higher uses than those commonly assigned to it, namely, of ministering to the often dull and inappreciative senses of man. We may detect a higher purpose in plant life than is included in the yet too common idea that man's delight and human interests exclusively determine and rule-through what some are pleased to call "the beneficence of providence "-the concerns of nature at large. The utilitarian cry of "use" and "no use" is by no means extinct, even in these latter days; and the consideration of the ways and means involved in the fertilisation of flowers must devolve a strong argument against the homocentric idea that the beautiful in nature exists solely for the behalf of man. Darwin says, "Such doctrines, if true, would be absolutely fatal to my theory." But there is little fear that the