Essays on the Microscope / Containing a Practical Description of the Most Improved Microscopes, a General History of Insects, etc., etc.

by George Adams

Fig. 20 to 24. S. Montanum. Linn. Long-leaved Meadow-saxifrage. This seed stripped of its foliaceous wings may be compared to a sort of canoo which is too narrow in proportion to its great length, has a hollow and a convex side, like that kind of boat, and is ridged longitudinally on its convex side, Fig. 20, from end to end, with four principal ridges; and between these, with others less considerable. There are, however, some of these seeds wider than others in proportion, but the majority are too long for their breadth, as I have said before.

These principal ridges are the support of the wings, and may be called their basis, for they rise broad from the body of the seed, and run out to a thin edge, which being continued constitute this leafy border. These are yellowish, and the spaces between them and the other less considerable ridges inclining to a brown.

On the concave side, Fig. 21, there is an edge or gunnel like that of a boat, and a considerable cavity from the edge; in the center of which the vestige of the stilus, Fig. 22, which is also bifid here, appears from one end to the other. The edge and this vestige are also of a yellowish colour, but the rest of the surface brown and porous, and the whole body of the seed and ridges shine, as if varnished over with some oily substance.

Fig. 23 is a view of the convex side of a seed divested of its wings, which is one of the most proportioned seeds I could pick out; at the upper extremity of which a little process may be perceived to turn or crook back upon the body; the same may also be discerned on that of Fig. 20. At the root of this process the opening or umbilicus of the seed lies.

Among the many beauties with which this seed abounds, there is one that is most agreeably surprising, which (says our author) I discovered by making a transverse section of one of them, in order to see what its internal substance consisted of. I no sooner applied the cut surface, Fig. 24, to my microscope, than each of the principal ridges, which I said above is the basis of the leafy wing, appeared to be a triangular tube, containing a fine brown liquid balsam of the colour of brown basilicon. This was a high entertainment, as every other curious discovery that arises by the diligent inspection of the seed is, and prompted my examining others in the same manner; and I found such a balsam as this common to the several kinds of parsley seeds also, as well as to that of the bishop’s weed and smallage; although these are so minute, that I could not be sensible of it but with difficulty, and with one of my greatest magnifiers. There is also something analogous to this in the sweet fennel and finoki, not in tubes of the husks or cortex, but rather in spungy channels that sink into the surface of the parenchyma, between the ridges of these last. The length of an ordinary seed is one-third of an inch, the thickness about an eighth, and the breadth of each wing nearly equal to the thickness of the body.

Hyoscyamus.

Fig. 25. H. Niger. Linn. Common Henbane. After the calyx has split and cracked by drying, the seed-pot comes to be exposed to the heat of the sun, which also grows dry, by which the lid or cover becomes loose, having no other visible attachment to keep it on the edge of the pot but its moisture, which in some measure helps to keep it there by agglutination, as well as by the squeezing or pressure of the segments of the calyx. But, this moisture exhaling, and the calyx splitting off, the lid, being now dry, blows off with the first blast of wind, and scatters the seeds, which by this time are hard and ripe.

When the seeds are ripe they are of a light colour, like white-brown paper, and incline to a triangular figure, whose angles are rounded off. They are depressed on both sides, so as to become pretty flat, and their whole surface is cellular; the cells have no particular form, but are somewhat irregular, and the ridges that form them are pretty eminent. As the drawing appears, the seeds may be said to have a basis and an apex; the former has no other particular mark than the cells, but the latter has a kind of notch indented downward from the top, which is the umbilicus of the seed. The parenchyma appears of a greyish colour. A middling grain is about a sixteenth of an inch long, and not quite so broad in the broadest part.

Cicer Rubrum.

Fig. 26 to 29. C. Arietinum. Linn. Chickpea. There is a good deal of reason for comparing the chiche grain to the head of a ram; for each of them, Fig. 26, consists of a round or back part, and an apex or snout. There are, besides this shape, which indeed favours the simile, several depressions upon the grain which add still to the likeness of that head; and these we shall consider in particular. On the upper or convex side there is, in most of them, a longitudinal little ridge, and a depression on each side, which resembles the rising in the frontal bone of a sheep; and, a little further forward, two risings, one on each side, which look like the superciliary eminences of the eyes. Each side of the round or occipital part has a depression that also adds to the same image; but what is yet a greater argument for it, is, that the under part, Fig. 27, is flattish, having an edge on each side, which may be compared to the edges of the under jaw. In the center of this flat part there is a little mamillary rising very remarkable, and just under the apex or snout an oval hole, whitish at the bottom, which is the umbilicus of the seed; besides which, there is an apparent sulcus on each side the apex, running a little way back, and is a close resemblance to the rictus oris. The husk is thin and fragile, and when taken off, looks like thin tortoise-shell; and the nucleus or parenchyma is of a yellowish white, exactly like the substance of a split-pea, without the covering. The entire nucleus has the same depressions which appear on its husk or cortex; and a fore view of it, Fig. 28, shews the naked apex, with the hole underneath, which is but superficial; and the seam which distinguishes the tip of the apex, I take to be the rudiment of the plant, for it is easily separated in that seam. The natural size of this seed appears, Fig. 29, being almost three-eighths of an inch from the apex to the outer edge of the basis, and something narrower.