The nature of the outer Coat is various, Membranous, Cartilaginous and Stony; the like Precipitations being sometimes made herein, as in a Stone or Shell; as in that of the Seeds of Carthamum, Lithospermum, and others. The Designment hereof, being either with respect to the Seed in its state of Generation; as where the Case is either wanting, or at least insufficient of it self, there for its due protection and warmth; or, in its state of Vegetation, for the better Fermenting of its Tinctures and Sap; the Fermentations of some Seeds not well proceeding, unless they lie in their Stony Casks in the Mould, like Bottled Liquors in Sand.
All Seeds have their outer Covers open; either by a particular Foramen, as in Beans, and other Pulse, as is said; or by the breaking off of the Seed from its Peduncle or Stool, as in those in Cucumber, Cycory; or by the entering and passage of a Branch or Branches, not only into the Concave thereof near the Cone, but also through the Cone it self; as in Shells and Stones.
For the sake of this aperture it is, that Akerns, Nuts, Beans, Cucumbers, and most other Seeds, are in their formation so placed, that the Radicle still standeth next to it; that, upon Vegetation, it may have a free and ready passage into the Mould.
The Original of the outer Coat, though from Parts of the same substantial nature, yet is differently made. In a Plum, the Seed-Branch which runs, as is described, through the Stone, is not naked, but, as is said, invested with a thin Parenchyma, which it carries from the Stalk along with it; and which, by the Ramification of the said Branch within the Stone, is in part dilated into a Coat. That of a Bean is from the Parenchyma of the Cod; the superficial part of which Parenchyma, upon the large peduncle of the Bean becoming a thin Cuticle, and upon the Bean it self a cartilaginous Coat.
The Original of the inner Coat of the Bean is likewise from the inner part of the said parenchyma; which first is spred into a long Cake, or that which with the seed-Branch maketh the peduncle of the Bean; under which Cake, there is usually a black part or spot; by the length of which, the inner part of the Cake is next inserted into the outer Coat, and spred all over the Concave thereof.
This inner Coat, though when the Seed is grown old and dry, ’tis shrunk up, and in most Seeds so far as scarcely to be discern’d; yet in its first and juvenile Constitution, is a very Spongy and Sappy Body; and is then likewise (as the Womb in a pregnant Animal) in proportion very thick and bulky; in a Bean, even as one of the Lobes it self: And in a Plum or apricot, I think I may safely say, half an hundred times thicker than afterwards, when it is dried and shrunk up; and can scarcely be distinguished from the upper Coat. Upon which Accounts it is, in this estate, a true and fair Parenchyma.
In this Inner Coat in a Bean, the Lignous Body or Seed-Branch is distributed: Sometimes, as in French-Beans, throughout the whole Coat; as it is in a Leaf: In the Great Garden-Bean, upon its first entrance, it is bipartite, and so in small Branches runs along the Circumference of the Coat, all meeting and making a kind of Reticulation against the Belly of the Bean. In the same manner the main Branches in the outer Coat of a Kernel, circling themselves on both hands from the place of their first entrance, at last meet, and mutually inosculate.
So that all the Parts of a Vegetable, the Root, Trunk, Branch, Leaf, Flower, Fruit and Seed, are still made up of two substantially different Bodies.