MY readers will remember that I referred to Haller’s statement, ‘Dimidium corporis humani gluten est,’ which applies to animals generally, viz. that half of their substance is gelatin, or that which by cookery becomes gelatin. This abundance depends upon the fact that the walls of the cells and the frame-work of the tissues are composed of this material. In the vegetable structure we encounter a close analogy to this. Cellular structure is still more clearly defined than in the animal, as may be easily seen with the help of a very moderate microscopic power. Pluck one of the fibrils that you see shooting down into the water of hyacinth glasses, or, failing one of these, any other succulent rootlet. Crush it between two pieces of glass and examine. At the end there is a loose spongy mass of rounded cells; these merge into oblong rectangular cells surrounding a central axis of spiral tube or tubes or greatly elongated cell structure. Take a thin slice of stem, or leaf, or flower, or bark, or pith, examine in like manner, and cellular structure of some kind will display itself, clearly demonstrating that whatever may be the contents of these round, oval, hexagonal, oblong, or otherwise regular or irregular cells, we cannot cook and eat any whole vegetable, or slice of vegetable, without encountering a large quantity of cell wall. It constitutes far more than half of the substance of most vegetables, and therefore demands prominent consideration. It exists in many forms with widely differing physical properties, but with very little variation in chemical composition, so little that in many chemical treatises cellular tissue, cellulose, lignin, and woody fibre are treated as chemically synonymous. Thus, Miller says: ‘Cellular tissue forms the groundwork of every plant, and when obtained in a pure state, its composition is the same, whatever may have been the nature of the plants which furnished it, though it may vary greatly in appearance and physical characters; thus, it is loose and spongy in the succulent shoots of germinating seeds, and in the roots of plants, such as the turnip and the potato; it is porous and elastic in the pith of the rush and the elder; it is flexible and tenacious in the fibres of hemp and flax; it is compact in the branches and wood of growing trees; and becomes very hard and dense in the shells of the filbert, the peach, the cocoanut, and the _Phytelephas_ or vegetable ivory.’ Its composition in all these cases is that of a _carbo-hydrate_, _i.e._ carbon united with the elements of water, which, by the way, should not be confounded with a _hydro-carbon_, or compound of carbon with hydrogen simply, such as petroleum, fats, essential oils, and resins.