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. [Illustration: _Nests of Spiders._] 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