SPARE HALF HOURS

Otago Witness, Issue 1899, 26 June 1890, Page 41

SPARE HALF HOURS

By F. A. Joseph.

Di-SIGN IN NATURE, i. Some scientists of the extreme materialistic school have attempted to account for the present constitution of things, as we find them on the globe, from the exclusive operation of what they are pleased to term natural forces. Now, while their position is not easily set aside by posifive evidence, yet there is no difficulty in proving them in error by the simple logic of deduction. When we see some noble steam ship, with graceful lines, cleaving the waves apart — meanwhile the throb of the mighty pulse that endows her with the power to breast the waves being felt throughout the ship— at once the mind is carried back to the architect who designed her graceful hull, and the euginecr who planned her wonderful machinery. Suoh a marine monster as a modern steam ship, whose course a baby hand could direct, in no small way displays the triumph or the human mind. Yet could some native fresh from the heart of " Darkest Africa " see such a phenomenon glide over the waters, as if endowed with life, like some leviathan afloat, and imagine that the beautiful ship with her marvellous engines was naturally evolved from the vasty deep, he would go no further than do the adherents of the materialistic school. We cannot, under the bright effulgence of the glorious light that has been borne in upon us in the closing decades of the nineteenth century, see a complicated piece of machinery, a, ship, or a bridge, without clearly recognising that the busy brain of thinking man has been at work ; neither can we, in the legitimate exercise of the same faculty of reason, see the wonderful design everywhere apparent throughout the widest domains of earth and space without recognising that the evident design prefigures the Designer Design without a designer would be like a void space. Let us briefly examine some of the more striking evidences of design in Nature. It is found that cross-fertilisation is necessary for the continued health of a plant, and there is not probably a single instance in which any plant is continuously self-fertilised. If those plants which are generally considered to be self-fertilising be carefully examined, it will be found that in reality the most complete provision is made to prevent self-fertilisaiion. There are in all four methods by which the cross -fertilisation of those simple plants bearing pistils and stamens within each flower is secured. By the first of these the anthers (bearing pollen) and the stigma (designed to receive the pollen) become mature at different times on the same plant. The result of this is that suoh a plant, with i!s mature stigma, can only be fertilised when some insect carries ripened pollen from another plant. In this way plants growing in dissimilar locations and soil will secure all the benefits of crossing. Again, a self-fertilising plant would in time become modified in harmony with its environment, with the result that varieties of the species would be indefinitely multiplied, and so great confusion would prevail ; but when cross-fertilisation is absolutely secured, in the manner above described, the average character of the species is maintained. The design here should be sufficiently apparent. By the second method the flower cannot be fertilised by its own pollen, while perfectly fertile with the pollen from a different plant of its kind. This peculiarity of some plants absolutely prevents self-fertilisation. In the case of some other plants the stamens are so placed that the ripened pollen cannot fall upon the stigma, while it does readily fall upon an insect as it visits the plant in search of nectar. This effect is very simply brought about in a variety of ways, the simplest being the bending down of the stamens out of the way of the stigma before the pollen is ripe. In yet another group of plants the male and female flowers are on lifferent plants, so that cross-fertilisation is absolutely insured. Such plants can only be fertilised by the agency of wind or of insects. And yet again it is found that the pollen from another plant often has a prepotent influenceover the plants' own pollen. In all these cases of course I refer to another plant of the same kind, for the most complete provision against crossing with even varieties of the same species is made. Some of the contrivances for securing the cross-fertilisa-tion of plants are wonderful, and had they been humanly designed we should term them ingenious. For a full description of these wonderful contrivances it will be necessary to consult Darwin's works oc the cros9 and self fertilisation of plants, and on the fertilisation of orchids.

In one group of plants (Lythrum) the contrivance for securing self-fertilisation iB rather remarkable. There are three different forms of flowers, one having the style much longer than the stamens ; in another tho style is rather shorter than the stamens, while in a third the style is very short. This plant is therefore said to be trimorphic. There are also some dimorphic plants. Now it is found that the pollen of a flower falis almost impotent upon its own stigma, while the plant is readily fertilised by the pollen from another plant whoso stamens correspond in length witli the style of the plant to bo fertilised. This Darwin called reciprocal dimorphism. The cross-fertilisation of the plants has been called legitimate, while selffertilisation is said to be illegitimate. In the trimorphic kinds legitimate unions may be formed between any two plants whose stamen and pistil (or style) correspond in length. As such* complete provision against self-fertilisation is made, it would not be in harmony with the economy of Nature that the pollen of a flower should fall uselessly upon its own pistil ; therefore the style is bent out of the way, and so placed that an insect visiting the flower is certain to touch it, while at the same time coming in conta3t with the stamens. The design in this peculiar arrangement is strikingly apparent. Some flowers have irritable stamens, so that an insect when sipping the nectar from the flower happens to touch the bases of the si amens they spring up, and so dust the insect with pollen. Others have a leverlike arrangement by which the pollen-laden anthers are brought down upon the back oJ

an insect visiting the flower. This is exemplified in the common salvia and several of the heaths. In some plants there is a sticky secretion, which gums pollen grains to the probsocisof an insect to be thereby carried to the next plant visited. In passing it might be well to note that a bee, or other insect at work gathering honey, keeps to flowers of the same kind and colour. Here is economy again, as the insect is the agent by which the flower is fertilised, and both insect and flower are thus necessary to each other. In some plants, as the lotus, there is a receptacle from which the poljen is squeezed out upon an insect, while in others the anthers explode and shoot the pollen over the insect, but this always takes place after the stigma has touched the insect, and taken-off some of the pollen from a flower previously visited. Some flowers close and entrap insects, and when they are fertilised they open again and release the prisoner. These are a few of the designs to secure the indispensable crossfertilisation of plants ; there are others to be considered yet.