CHAPTER II.

STRUCTURE AND CONTENTS OF THE EGG.

In the past pages we have now considered shortly the various methods of depositing the eggs of insects, and have seen that the nursing place where the young being is produced, differs widely both in point of its position, and of the external circumstances which variously affect it. For some are the deep-bored galleries in timber; for some, the hard-wrought tunnel, scooped by an insect out of a rock; for some, the ingeniously-formed boat or raft, which is to carry its cargo of life buoyant on the dancing waters "all the days of its appointed time, waiting until its change come;" for some, the cell of earth lined with painted hangings, exquisite in make and colour; for some, the little leaf-case, curiously folded together; but for others, none of those works of insect art are provided; they, hid in a rain-proof covering of varnish, lie open to every eye, or scattered here and there on all and every kind of flower and herbage, lie at the mercy of every wandering foot. While, lastly, others are buried with a cruel yet merciful art, in the bodies of myriads of unsuspecting members of the insect community, lying, like the seeds of evil in the heart of the infant, dormant awhile, but destined to grow with its growth and to strengthen with its strength.

The time has, therefore, now come that we should speak a little more particularly upon the nature and character of the eggs of insects. The shape of an insect's egg, although frequently something of an oval in its outline, is very various; in fact, were the egg of some peculiar species placed in the field of a microscope, probably not one general observer out of a hundred could in the least imagine what the object at which he was looking really was. Sometimes they are oval and exactly resemble the form of the egg of the bird; but in other instances they are of the most irregular and fantastic appearance. Some look like pill-boxes tied over and down their sides with string; others look like tiny flasks, with many raised ribs upon their surface; others have lids and springs. The gnat's egg resembles a chemist's phial, or one of the new bottles for holding aërated waters; and those of the dung-fly have two little pieces sticking out at the top on each side to prevent them sinking too deep into the matter upon which they are deposited.

The eggs of some insects strikingly resemble the little shells like turbans with which we are most of us familiar. A very singular variety of egg which has often caused much perplexity to naturalists is the egg of the lace-winged fly. Réaumer says, "I had observed them several years without actually knowing what they were. Others as well as myself had noticed that on the leaves and twigs of many trees were a number of minute stalks placed together, scarcely as thick as a hair, their colour was nearly white, and they were about an inch in length; there were sometimes ten or twelve placed in a bunch; the end of each stalk bore a small head of an egg-like or oblong figure. They appeared to me to be fungi, the little head precisely resembling the appearance of moulds as seen under the microscope; but they were larger in size." They were, in fact, the eggs of the fly in question. When the larva escapes from them they have much the appearance of little vases; and the same author assures us that they were once described and engraved by a naturalist as some curious minute flower growing on the leaves of the elder, for which he was unable to account. The representation of them in the cut will enable the reader to form his own opinion as to the difficulty of ascertaining whether they were flowers or the nests of an insect.

The manner in which these eggs are thus regularly placed by the insect is interesting. Placing herself upon the leaf in the attitude represented, she fastens a thread to the leaf, draws it out in the same way as a spider does her lines, and when it has got sufficiently firm the wise insect then puts forth the egg, glueing it to the extremity of the stalk; this done, she quits it and begins to form another, repeating the same actions until the proper number is laid. Poised on the summit of these slender pillars the eggs are secure from every invader but man himself, and in time there comes from them the larva which is to become the beautiful insect, the "lace-winged fly," in all the elegance of its form.

From what has been already stated, the surface of the eggs of insects, it will be perceived, is by no means in all cases smooth and polished as in the case of birds. Far otherwise. To look at some of them by the help of a magnifying glass we should imagine that they were covered with very fine lace net, others appear as if some clever engraver had been chasing some intricate design upon their surface. The eggs of a species of butterfly are studded over with an infinite number of little knots or tubercles; and those of another are capped at the top with sculptured work disposed in the form of a circular tiling or roof to the egg. Some also closely resemble embossed buttons.

He who has thus adorned these minute objects with beauty of form and carving, has likewise bestowed upon them the most beautiful and variegated colours--colours such as no human art can imitate. But from the small size of the eggs it is difficult to appreciate this beauty in them except when they occur in a mass. The most common tints are white, yellow, and green, but the richer and rarer hues are also to be found among them. Thus, the eggs of a moth are of a beautiful blue colour, banded in the most delicate manner by three zones or rings of brown, the contrast being very pleasing. Another moth, which loves to deposit its eggs in the bark of the willow, produces them tinged with a purple more delicate than ever Tyrian lady wore as the finest produce of the dyer's art. In the deep crevices of the bark of the elm, and only, therefore, to be found by sharp scrutiny, another moth lays eggs of a lovely pink. Messrs. Kirby and Spence write, "We remember once being much surprised at seeing the water at one end of a canal in our garden as red as blood; upon examining it further we found it discoloured by an infinite number of minute red eggs." Sometimes eggs are spotted, and thus resemble the eggs of many birds; and, strange to say, sometimes they change colour in a very remarkable manner; so that, as far as colour is concerned, an observer could scarcely believe that the egg was the same he beheld, perhaps, a few days previously. The eggs of the chameleon fly, as we are told by the gentlemen last quoted, are at first pure white; then change to green, and finally turn to a deep olive-green. Others are at first mouse-coloured, then reddish, and, lastly, black. The eggs of a kind of moth we have seen first of the colour of sulphur, then becoming _green_, after that _rose-colour_, and lastly, _black_. In the instances of the common gnat and silk-worm, similar changes of colour take place. The eggs of the gnat are first white, then green, and finally gray; and those of the silk-worm are in the first instance of a pale yellow, and ultimately take on a violet tint.

Having thus noticed these points in connexion with the Life of an Insect, we are led to that most important of all periods, the dawn of life in the egg, or, in common terms, the period of hatching. But before proceeding to the subject, may we not pause and wonder as we behold the varied manifestations of the Creator's wisdom in the actions of the minute, and, as we often call them, insignificant creatures of whom we have spoken? Should David say, when he beheld the sun, moon, and stars, as the work of a Divine hand, "Lord, what is man, that thou considerest him, or the son of man, that thou regardest him!" And shall not we, as we contemplate the few particulars here set down of the wonders of insect-life, exclaim, with even greater astonishment, "What are these, that thou considerest _them_?" Let no one then say, that entomology, or any other natural science whose field of study lies chiefly among the minute portions of creation, are profitless sciences, when they can reveal to us such a display of the power, wisdom, and love of God, as is exhibited even in this small portion of the Life of an Insect.

Let us then take up one of these eggs, so minute, but containing within it the rudiments of a being which is in time to assume a form of considerable magnitude, by comparison, and to be adorned with colours richer than art can boast of, and let us examine it on the field of a tolerably powerful microscope. We need not look far for a specimen. In the dark corner of the ceiling in a neglected room, after removing the mass of dust-filled webs that have accumulated there for months, we may find without difficulty a spider's nest of eggs. A more pleasant place to search for insects' eggs is, perhaps, the garden; and if in the crevices of the bark of the trees, or attached to twigs or branches, none can be found, we can almost certainly promise success if the reader will carefully and patiently search the angles of the garden walls, particularly if he has noticed in the preceding autumn many of the beautiful webs of the garden-spider. There, in some sheltered recess, where the pattering rain-drops may be heard, but never venture in, and where few eyes would detect them, may be found little round yellow balls, of the size of a small cherry, made of the most beautiful golden-coloured silk, and attached by a slender stalk to the wall, or perhaps, to a twig. Sometimes they exhibit the more elegant and curious appearance shown in the figure on the next page, resembling an inverted wine-glass or pear.

On taking our prize in-doors, by the aid of a very sharp penknife we may succeed in cutting it smoothly open, and in turning out some of the delicate eggs which lie warmly covered up at the bottom. Taking one of them up on the point of the knife, and laying it on the microscope-field, we shall be able to see something of the anatomy of an insect's egg.

First, we may notice what seems to be the shell; that is, the outer covering of the egg. This is very different to the hard, calcareous eggshell of birds. It is stated not to contain any lime in its composition as the shells of birds do; for when the eggs of insects are put into very weak sulphuric acid and water, which would act on the lime if it were present in their composition, they are not affected by it. Although, therefore some eggs of insects are very hard: so hard indeed as to resist severe pressure with the nail, they do not owe their hardness, as do the eggs of birds, to any lime in their chemical composition. The outer coat or shell is apparently simply membraneous, frequently varying greatly in thickness, being sometimes as dense and horny as we have mentioned, and at others, so delicate as to burst with the gentlest touch.

Could we now do, what it is so easy to do with the egg of a fowl,--carefully take off a little portion of this outer shell, we should be able to inspect its contents more accurately. But in the case of most who read this book, this extremely delicate task will prove after many trials probably a hopeless failure. Let us state, therefore, what some expert and talented observers have found within the insect's egg. It appears, then, that although there is both a "yolk" and a "white" in the tiny egg before us, that they are not quite so distinct as in the bird. Yet, they are sufficiently separate from one another to make their differences complete. Probably the reader has noticed in the hen's egg a little round spot in the middle of the "yolk" or yellow portion; from this the future bird is produced. Although from their extreme minuteness it is difficult to detect anything of this kind in the eggs of insects, some observers state they have seen a similar little spot in them also. Thus, M. Herold says, that in the eggs of the very insect whose nest we have robbed, the garden spider, "this little spot can be seen as a minute white point immediately under the shell, and in the middle of its circumference." This was seen by holding it up to the light, and the spot was more carefully examined by gently pressing the contents of a spider's egg upon a watch-glass. Mr. Rennie says, that "the point where the caterpillar originates, answering to the scar in the eggs of birds, we can readily distinguish even by the naked eye in the larger species of eggs, as it lies always immediately under the shell." But it may be doubted whether, without the assistance of some one versed in entomology, many who make the same attempt, will succeed. So much depends in looking at any object upon whether we know what to look for or not, so that things which are as clearly seen as possible by the eyes of the initiated, are not seen at all by any others. To perceive some things in natural history, and many in science, the senses of sight, hearing, and touch, require to be well educated, and they then become apparent enough.

And is this all that we can mention about the structure of an egg? This indeed is all. Can it be possible? Is there no striking and broad difference to mark the nature of the future insect? Is the egg of a spider the same in the number and nature of its parts as that of a butterfly, or the egg of a gnat as that of a beetle? Surely, as we should imagine, there must be some important differences between these, otherwise why such immense differences in the perfect insect? Could any one imagine that a grasshopper and a house-fly, so strangely unlike each other in their perfect forms, originated in eggs to either of which the same description of an insect's egg would accurately answer, and leave nothing out? However great our amazement, the fact is unquestionable. The egg of every insect at first consists of an outer covering, a white, a yolk, and the little spot we have alluded to. We might have thought that in creating so many different species of insects, which differ so surprisingly in form as the insect tribes do, the great Creator would have formed their eggs essentially different too. But, except in the matter of shape, all are originally alike; and the wisest philosopher is unable to inform us of any essential difference in the eggs of insects at first. The eye of God, who knows the end from the beginning, sees some difference inappreciable to the eye of man. He said to this kind, "Be thou thus," and to that, "Be thou different;" but until the time comes when the young insect is much more advanced, it is not possible for us to recognise those marks of variety which His hand has laid upon them from the beginning.