The =spermoderm= is the thin, brown, granular-appearing skin of the almond. The layers of the spermoderm are the epidermis, the hypoderm, the middle layers, and the inner epidermis.
The =epidermis= consists of radially elongated, thick-walled stone cells which occur alone or in groups of two or more, but seldom as a continuous layer. The upper or outer part of the stone cells is non-porous, but the inner walls are strongly porous (Plate 123, Fig. 1).
The =hypoderm=. The cells forming the hypoderm are compressed, the wall structure is practically indistinguishable, and the whole mass is reddish brown (Plate 123, Fig. 2).
Occurring in this brown layer are several vascular bundles (Plate 123, Fig. 3).
1. Epidermis. 2. Hypoderm. 3. Vascular bundle. 4. Middle layer. 5. Inner epidermis. 6. Endosperm. 7. Outer layer of the embryo. 8. Inner layers of the embryo.]
The =middle layers=. The cells forming the middle layers (Fig. 4) have thin, wavy, light-colored walls which are frequently compressed, and it is with much difficulty that their outlines are made out.
The =inner epidermis=. The cells forming the inner epidermis are rectangular in form, and they contain reddish-brown cell contents (Plate 123, Fig. 5).
The =endosperm=. The cells forming the endosperm are large, rectangular in outline, usually one layer thick, and they contain aleurone grains.
The =embryo=. The cells forming the outer layer of the embryo are smaller than the inner layers, and they are immediately inward from the layer of endosperm cells (Plate 123, Fig. 7).
The cells forming the greater part of the embryo are large, rounded, and they contain aleurone grains and fixed oil (Plate 123, Fig. 8).
In white and black mustard are characteristic mucilage and palisade cells.
In mix vomica, stropanthus, and St. Ignatius’s bean are characteristic hairs.
In physostigma and kola are characteristic starch grains.
In henbane, capsicum, stramonium, lobelia, and belladonna seeds are characteristic epidermal cells.
In areca nut, colchicum, saw palmetto, and nux vomica are characteristic thick-walled, reserve cellulose cells.
In cardamon seed are aggregate starch masses with irregular outlines.
In bitter and sweet almond, linseed, pepo, and stropanthus are aleurone grains.