large cells can be broken by the finger and thumb, while the small cells cannot be opened without the knife.

The insects themselves are equally variable, some being mere dots of shining blue and green, while others are about as large as the common red ant of the gardens, but with plumper bodies. In consequence of these two facts, the large, strong-jawed insect can easily make its way through the comparatively thin walls of the large cell in which it was enclosed, while the small and necessarily weak-jawed specimens are utterly unable to pierce the walls of their cells, which are so thick that they must bore a hole equal in length to that of their whole body before they can escape into the air. Consequently, the great mass of the insects that are found in the cells are the small specimens, the larger having made their escape. I find that on an average twenty small insects are thus found in proportion to one of the larger kind.

Nothing is easier than the rearing of insects from this as well as other galls, but to decide upon the species which make them is by no means so easy a task as appears on the surface. Even should the experimenter find the right species of insect in the gauze bag, he has to go through the wearisome task of searching through the family of Cynipidæ, and identifying the species-a process which every entomologist is rather apt to postpone until the visionary period when he shall have leisure.

But it is very probable that the required insect does not make its appearance at all, and that the little hymenoptera which make their way out of the cells, or are found dead within them, are not the rightful occupants of the galls. For the Cynipida are as liable to parasites as other insects, and it frequently happens that from a single many-chambered gall will issue insects that sadly puzzle an amateur, as they seem to belong to at least two distinct species. The very gall which has just been described affords a good example of this fact, for in some of the chambers are specimens of the true Cynips rose, and in others are insects which belong to another family, the Ichneumonidæ, which, as the reader may remember, are parasites upon other insects. They have evidently introduced their eggs into the cells occupied by the larvæ of Cynips rosa, so that the larvæ which have been hatched from these eggs have fed upon the

legitimate occupants, and come to maturity in the cells that were designed for others.

Insects of totally different orders sometimes make their appearance. When I began to take to pieces the gall which has been described, I was rather surprised to find among the long hairs an empty cocoon of the Galleria moth, whose ravages have been mentioned in an earlier part of the volume. On further dissecting the gall, no less than twelve other cocoons were found, all buried so deeply in the hairs and among the woody cells that they could not be seen until the hairy clothing was removed. A person who was entirely ignorant of entomology might naturally fancy that the moths were the architects of the gall from which they had apparently issued. How they obtained access to the galls, and on what food they lived, are two problems that I can by no means solve. The drawer in which the galls were placed is tightly closed, and all bee, wasp, and hornet combs have been so treated with corrosive sublimate, that they have not been touched by the caterpillars from which the moths had been developed.

THERE is another gall, very common in England, which is found upon the oak, and which is generally thought, by persons who are unacquainted with botany or entomology, to be the buds which naturally grow upon the tree.

In these curious galls, the excrescences with which they are covered take the form of leaves instead of hairs, as is the case with the bedeguar and many other galls. These bud-like objects may be found on the young twigs, and may be easily recognised by their shape, which somewhat resembles that of a pine-apple, and the curious manner in which their leafy covering lies regularly over them, like the tiles upon an ornamental roof. The size of the gall is rather variable, but it is, on an average, about as large as an ordinary hazel-nut.

The gall is so wonderfully bud-like that I have known the two objects to be confounded-the immature acorns in their cups to be carried off as galls, while the real galls were left on the tree. The incipient naturalist who made the mistake kept. the buds for some eighteen months, and was sadly disappointed to find that no insects were produced from them.

The insect whose acrid injection produces this curious effect

upon the tree is rather larger than the leaf-gall insect, and is of more slender proportions. It has been suggested that the object of the leafy or hairy covering is, that the insect, which remains in the gall throughout the winter, should have a warm house by which it may be protected from the chilling frost as well as from the wind and rain.

IF the reader will again refer to the illustration, he will see that from the same branch on which the Cynips Kollari has formed so many galls, depend two slender threads supporting one or two globular objects. These are popularly called CURRANT-GALLS, because they look very much like bunches of currants from which the greater part of the fruit has been removed. Their colour, too, is another reason for giving them this name, as they are sometimes scarlet, resembling red currants, and sometimes pale cream colour, thus imitating the white variety.

These galls are placed upon the catkins of the oak, which are forced to give all their juices to the increase of the gall, instead of employing them on their own development. Some authors think that the insect which forms them is a distinct species, while others think that the galls are the production of the same insect which forms the leaf-gall, the punctures being made in the stalk of the catkin and not in the nervure of the leaf.

That this supposition may be correct is evident from the fact that the same insect which forms the oak-apples does also deposit its eggs in the root of the same tree, causing large excrescences to spring therefrom, each excrescence being filled with insects. I have often obtained these root-galls, several of which are now before me, some having been cut open, in order to show the numerous cells with which they are filled, and others left untouched, in order to exhibit the form of the exterior. Being nourished by the juices of the root, they partake of the sombre hues which characterise the part of the tree from which they spring, and do not display any of the colours which are seen on the oak-apples which spring from the twigs.

There are, however, distinct species of gall insects which pierce the roots of the oak-tree. One of them is termed Cynips aptera, and makes a pear-shaped gall about one-third of an inch in

diameter. Each gall contains a single insect, and a number of the galls are often found attached by their narrow end to the root-twigs of the tree, something like a bunch of nuts on a branch. There is another insect which is termed Cynips quercusradicis, which forms a many-chambered gall of enormous size, containing a small army of insects. Mr. Westwood mentions that one of these galls in his possession was five inches long, one inch and a quarter wide, and produced eleven hundred insects, so that the entire number was probably fourteen or fifteen hundred.

No one who is accustomed to notice the objects which immediately surround him can have failed to observe the curious little galls which stud the leaves of several trees, and which are appropriately called SPANGLE-GALLS, because they are as circular, and nearly as flat, as metallic spangles.

These objects had been observed for many years, but no one knew precisely whether their growth was due to animal or vegetable agency. That their substance was vegetable was a fact easily settled, but some botanists thought that they were merely a kind of fungus or lichen, while others supposed that they were the work of some parasitic insect.

When closely examined, these "spangles" are seen to be discs, very nearly but not quite flat, fastened to the leaf by a very small and short central footstalk. Reaumur set at rest the question of their origin by discovering beneath each of them the larva of some minute insect, but he could not ascertain the insect into which the larva would in process of time be developed. The task of rearing the perfect insect from the gall is exceedingly difficult, the minuteness of the species and the peculiar manner in which the development takes place, being two obstacles which require a vast expenditure of care and patience before they can be

overcome.

Supposing a branch containing a number of infested leaves to be placed in water and surrounded with gauze, it will die in a week or two, and yet there will be no sign of an insect. If the branch be kept until the winter has fully set in, the desired insects will still be absent, and the experimenter will probably think that his trouble has been thrown away. The real fact is, that the little insects are not developed until the spring of the

following year, and that they pass through their stages of the pupal and perfect forms after the leaves have fallen, and while they are still lying on the ground.

Mr. F. Smith, who has given so much time and research to the history of the hymenoptera, has discovered the insect that inhabited the galls to be Cynips longipennis, and has remarked that the perfect insects do not make their appearance until the month of March.

WE now pass from the British galls to those which are found in various other countries. A few of the more interesting examples are figured in the accompanying illustration.

Should the reader have the curiosity to examine for himself the structure of the British galls (as I trust he will do) he will find that when he cuts a juicy specimen, such as that of the leaf-gall, his fingers will presently be stained with purple-black. He may wash his hands as much as he likes, but he will not wash away the stain, which soon looks as if it had been produced by spilling ink on the hands. There is reason for such an ap