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Ants and Aphide.

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their metamorphosis, build cells and feed the larvae of their captors.

Some ants are sure to be found on the plants crowded with Aphida; not to harm, but to rub them gently with their antennæ ; then the Aphidæ, apparently pleased, distil a little drop of sugary liquid which the ants sip up-using the Aphidæ as cows. Hundreds of observations prove that these industrious creatures communicate with and understand one another. They may be seen to stop, and touch one another with their antennæ, which seem to be special organs of a peculiar insect language. Wounded brethren are helped and led to the nest, operations are conducted and battles are fought in military array.

Aphidæ present curious and interesting facts. The males have large wings, but nearly all the females are without wings. In autumn their eggs are laid on plants; hatched in the spring, not as caterpillars or grubs, but imperfect Aphidæ, all females. These females are the mothers of millions and millions like themselves-wingless females-to nine or ten generations. Then the last generation does not produce its like, but perfect males and females with wings, which lay eggs in autumn to be hatched in spring. Only the first generation of imperfect females is hatched from eggs, all the rest are born alive at the rate of three, four, or seven a day; but the last generation have inside buds which, when born, are not like their mothers, but resemble the parents which laid eggs the year before. This anomalous system of reproduction is known as parthenogenesis, breaking the rule-that like produces like.

The glories of the perfect insect are not marked in the tiny grub. Important organs and new combinations of structure are added and shaped by the power of growth and metamorphosis. Adult parts are not seen in the egg of an insect, nor is our own spirit found by anatomical research in the dead body.

Some insects, like Grasshoppers, change their skins several times during growth. There are changes inside the egg, and moultings and metamorphoses outside, during the history of most of the Articulata. Some change so greatly as to become wholly different, others submit but to slight changes of shape and structure. Things very similar end in differences most striking; nevertheless, between the immature

and adult forms anatomy discovers close resemblance. The lobster and the prawn, for example, are closely allied by similarity of construction; but the former changes little, the latter presents three forms before attaining the mature beauty of prawn life; which revealeth, even in prawn life, the symmetry of Providence.

The Death's Head Moth can squeak. Caterpillars, Attacus æcropia, from Louisiana, at first nearly black, decorated with hairs, look like little hedgehogs. Moulting, they become grey-green or russet in colour, and the tubercles or spines brilliantly black. Again moulting, they are bright green with five rows of black spots; two magnificent tubercles of a carmine colour are on the second and third segments, and two of light yellow are on the dorsal part of every other segment. At a third moult, the body is azure blue on the back with black spots on the sides and head; the tubercles form two rows on the back, are red and much enlarged; the other tubercles have a single spine upon them. At the last moult the caterpillar is of a pale green colour, all the lateral tubercles are light green, the red tubercles take an orange tint and have only one spine. Then it forms a double cocoon-the outside hard and like parchment in texture, the interior silky-where it is transformed into the moth.1 Many are the resources of contrivance, and need to be studied would we know the wonder-working alchemy.

Some caterpillars fast for nine months; larvæ of the next kind eat and grow big. Metamorphosis is not determined by simple physical influences, it often refers back to ancestral peculiarities. The processional caterpillars go forth under a leader to their food, return in the same array, yet nothing distinguishes the leader from the others. Caterpillars, much alike, become moths with peculiar marked distinctions; and moths, which resemble one another, proceed from very dissimilar caterpillars. Passings on and changes are like our thoughts, which metamorphose the images within our ken, that we may know the riches stored in God's every creature.

Metamorphoses are generally an advance, but the female winter moth, Climata brumata, and Psyche, positively retrograde; the male advances, has wings, but the female is "Transformations of Insects," p. III: Dr. P. Martin Duncan,

F.R.S.

Purpose in Everything.

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without even the moving power of the caterpillar: whereas, the females of a Nemoura are perfectly developed as winged flies but the wings of the males are rudimentary and short. Of the Psyche helix moth, we only know the female; the virgin females lay eggs which become perfect females. In like manner, isolated female wasps give birth to eggs which turn to females, no males; which again produce their like.' He that wondereth hath a store of pleasure.

The Hymenoptera, most highly endowed of all insects, are in an early stage most helpless; the larvæ of ants must have the food put into their mouths. On the other hand, the instinct, or sense of hearing, or of smell, that enables the parasitic Hymenoptera to discover a larva inside a fruit, or within the branch or trunk of a tree, and perfectly out of sight, makes us wonder. Some non-carnivorous insects hunt and catch prey for their carnivorous young; then stupefy the prey so that it may remain alive, even months in helpless state, for the young to feed on. All known Beetles lay eggs, but in 1864 Schiödte discovered that the Staphylinide produced living larvæ. All the Myriapods respire by agency of tracheæ, but Sir John Lubbock describes a curious little myriapod, Pauropus, which has a look of cheerful intelligence, no trachea, and respires, he supposes, through the skin. All these varieties, of which natural uniformity is the theatre for display, are indications of a mysterious energy working in peculiar ways, adjusting inner and outer relations; and, however elevated and complicated the result, it is wrought by means of the simplest elements, and generally by insensible degrees.

Nature seems to have a purpose in everything, and works as knowing how to do it, though the purposeless or "silent members" in animal frames are hard to account for. Some animals have teeth, never meant to eat with; the rudiments of toes in a horse, and teats in male animals, are utterly useless. Are we to infer that eyes are not meant to see with; nor feet to walk with; nor teeth to eat with; nor was "a duck expressly intended to be a duck with a web-foot, that it might pleasantly move on the water; but forefathers and mothers a long way back began, under pressing circumstances, to get a duckish disposition; and by

1 "Transformations of Insects," pp. 158, 238: Dr. P. Martin Duncan, F.R.S.

dint of endeavour for ages to try their chance of paddling themselves about on the pools of a puddly world; were at length rewarded with success remarkable. A generation sprang from them thoroughly equipped for the waters with web-feet, oily back, boat-shaped bodies, spoony bills, and bowels to correspond with mudworms and duckweed?"1 Surely it is time to lay aside notions so grotesque, and to live, as did Newton and Boyle, in the conception that

"God dwells within, and moves the world and moulds,
Himself and Nature in one form enfolds."

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Goethe.

Not able to assign a purpose for purposeless structures, we are less able to account them as natural selections :-they are unnatural. Creatures could not, nor would, voluntarily grow them; nor attempt, by purposeless structures, to become intelligent. It is incredible that any animal putting swiftness from the feet, fangs from the mouth, claws from the paws, acute sense of smell from the nostrils, did thereby advance in life. As for time and space, they are not structural causes. If, however, we consider that "silent members were of use in the past, or are for use in the future; that there is in Nature an agency of use and disuse; light begins to shine. We see somewhat of the stages by which old forms die out and new forms come in: by modifications of ancestral organisms. There is another explanation :-The finished complicate parts of machinery are all typified in simpler shape, and narrower use in smaller or primitive engines: the imperfect organs of lower animals become perfect in higher creatures. In like manner, the human mind, in its growth, is a real though faint emblem of the progress which all natural phenomena manifest. We have a sketch, in ourselves, of the detail and plan which are worked into the universal fabric: the lower anticipates the higher, the higher fulfils that anticipation.

The battle of life represents an unseen influence, visible in effect, taking away the feeble, laying aside the lame, carrying off the blind; that the strong, the swift, the clear-sighted, may not be hindered. "Life is not a bully who swaggers out into the open universe, upsetting the laws of energy in all directions, but rather a consummate strategist, who, "The First Man and his Place in Creation," p. 36: George Moore, M.D.

Science of Experimental Surprises.

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sitting in his secret chamber over his wires, directs the movements of a great army," and leads his forces to possess the world.

The Manifold Changes of Inorganic Matter.

Chemistry is the science of experimental surprises. The most inert substances often produce, by combination, compounds of the strongest energy; the tasteless becomes intensely sour, sweet, or bitter; water, that quenches fire, contains the elements of fire; and things which give and gladden life turn into demons of destruction. The chemical union of different kinds of atoms, in definite proportions of numbers, changes their characters and properties. Paint, made to absorb and retain bright light, becomes luminous in the dark. Two different liquids often condense into a solid; and the result of the chemical combination of two various gases or vapours, in quantitive proportions, may be solid, liquid, or aeriform. The ingredients of that acrid, dangerous, corrosive liquid, aquafortis, in different proportions, are constituents of the summer breeze. Another affinity of our atmosphere produces "laughing gas." There are compound substances, identical in the number and relative proportions of elements, which in colour, odour, taste, are wholly unlike. The same substance will act as an acid in one combination, and as a base in another. Chemical laws seem imperfectly stated cases of some more general law of combination. When we gather profit with pleasure advantage is amusement.

A piece of sugar falls into water, sinks by law of gravity; but, in a little while, is found to pervade and sweeten the whole. The same happens with salt, alum, and various other substances; yet, oil poured on the water will not diffuse itself through the mass; and gases of different densities put into a vessel will not retain different levels according to gravity, but commingle, by the law of diffusion.

Every different body requires a different quantity of heat to produce in it the same change of temperature; and the volume of most substances increases continuously as the temperature rises; but there is at least one exception among solid bodies-Iodide of Silver. The three principal states of matter are the solid, liquid, gaseous; but most substances, probably all, exist in every one of these states. The solid, passing into the liquid state, is hotter than the liquid-the "The Unseen Universe,”

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