A great desideratum in pomological science is, a system of classification for the apple, founded on characters which are at once permanent and well defined. The Germans have been most assiduous in endeavoring to attain this object, and many systems have been suggested, of which those of Manger, Sickler, Christ, and Diel, are most generally known. But it is to Diel that the greatest merit is due, for having produced a system, which, though far from perfect, is greatly in advance of any which had hitherto been produced; and which has been universally adopted by all the German pomologists. In 1847, my friend Dochnahl, an eminent and assiduous pomologist, published a system, based upon that of Diel, of which it is a modification, and which possesses such advantages over its type, as to be more easily reduced to practise. As the systems of Diel and Dochnahl, are certainly the best which have yet appeared, I have introduced them here, for the benefit of those who may want a groundwork on which to form an arrangement. DIEL’S CLASSIFICATION. CLASS I. RIBBED APPLES. 1. They are furnished with very prominent, but regular ribs round the eye, extending also over the fruit, but which do not render the shape irregular.--2. Having wide, open, and very irregular cells. ORDER I. TRUE CALVILLES. 1. They taper from about the middle of the fruit towards the eye.--2. They are covered with bloom when on the tree.--3. They have, or acquire by keeping, an unctuous skin.--4. They are not distinctly and purely striped.--5. They have light, spongy, delicate flesh.--6. They have a strawberry or raspberry flavor. ORDER II. SCHLOTTERÄPFEL. 1. The skin does not feel unctuous.--2. They are not covered with bloom.--3. They are either of a flat, conical, cylindrical, or tapering form.--4. They have not a balsamic, but mostly a sweetish or sourish flavor.--5. They have a granulous, loose, and coarse-grained flesh. ORDER III. GULDERLINGE. 1. They are not balsamic like Order I., but of an aromatic flavor.--2. They have a fine flesh, almost like that of the Reinettes.--3. They are either of a conical or flat shape.--4. They are most prominently ribbed round the eye. CLASS II. ROSENÄPFEL.--ROSE APPLES. 1. They are covered with blue bloom when on the tree.--2. They have not unproportionally large, but often only regular cells.--3. They emit a pleasant odor when briskly rubbed.--4. The skin does not feel unctuous.--5. They are handsomely and regularly ribbed round the eye, and often also over the fruit.--6. They have a tender, loose, spongy, and mostly fine-grained flesh.--7. They have a fine rose, fennel, or anise flavor.--8. They are mostly of short duration, and are often only summer, or autumn apples.--9. They are mostly striped like a tulip. ORDER I. FRUIT TAPERING OR OBLONG. ORDER II. FRUIT ROUND OR FLAT. CLASS III. RAMBOURS.