A remarkably pretty example of stomata and elongated cells is to be obtained from the leaf of the common iris, and may be prepared for the microscope by simply tearing off a strip of the epidermis from the under side of the leaf, laying it on a slide, putting a little water on it, and covering it with a piece of thin glass. (See Plate II. Fig. 2.) There are a number of longitudinal bands running along the leaf where these cells and stomata appear. The latter are not placed at regular intervals, for it often happens that the whole field of the microscope will be filled with cells without a single stoma, whilst elsewhere a group of three or four may be seen clustered closely together. Fig. 3 on the same Plate exhibits a specimen of the beautifully waved cells, without mouths, which are found on the upper surface of the ivy leaf. These are difficult to arrange from the fresh leaf, but are easily shown by steeping the leaf in water for some time, and then tearing away the cuticle. The same process may be adopted with many leaves and cuticles, and in some cases the immersion must be continued for many days, and the process of decomposition aided by a very little nitric acid in the water, or by boiling. On the same Plate are three examples of spiral and ringed vessels, types of an endless variety of these beautiful and interesting structures. Fig. 4 is a specimen of a spiral vessel taken from the lily, and is a beautiful example of a double spire. The deposit which forms this spiral is very strong, and it is to the vast number of these vessels that the stalk owes its well-known elasticity. In many cases the spiral vessels are sufficiently strong to be visible to the naked eye, and to bear uncoiling. For example, if a leaf-stalk of geranium be broken across, and the two fragments gently drawn asunder, a great number of threads, drawn from the spiral vessels, will be seen connecting the broken ends. In this case the delicate membranous walls of the vessel are torn apart, and the stronger fibre which is coiled spirally within it unrolls itself in proportion to the force employed. In many cases these fibres are so strong that they will sustain the weight of an inch or so of the stalk. In Fig. 5 is seen a still more bold and complex form of this curious structure; being a coil of five threads, laid closely against each other, and forming, while remaining in their natural position, an almost continuous tube. This specimen is taken from the root of the water lily, and requires some little care to exhibit its structure properly.