have lately discover'd like those of a Sponge, and perhaps all these three bodies may be of the same kind of substance, though two of them indeed are commonly accounted Vegetable (which, whether they be so or no, I shall not now dispute) But this seems common to all three, that they undergo a tanning or dressing, whereby the interspers'd juices are wasted and wash'd away before the texture of them can be discover'd.
What their way is of dressing, or curing Sponges, I confess, I cannot learn; but the way of dressing Spunk, is, by boiling it a good while in a strong Lixivium, and then beating it very well; and the manner of dressing Leather is sufficiently known.
It were indeed extremely desirable, if such a way could be found whereby the Parenchyma or flesh of the Muscles, and several other parts of the body might[errata 1], might be wash'd, or wafted clean away, without vitiating the form of the fibrous parts or vessells of it, for hereby the texture of those parts, by the help of a good Microscope, might be most accurately found.
But to digress no further, we may, from this discovery of the Microscope, plainly enough understand how the skin, though it looks so close as it does, comes to give a passage to so vast a quantity of excrementitious substances, as the diligent Sanctorius has excellently observed it to do, in his medicina statica; for it seems very probable, from the texture after dressing, that there are an infinit of pores that every way pierce it, and that those pores are onely fill'd with some kind of juice, or some very pulpy soft substance, and thereby the steams may almost as easily find a passage through such a fluid vehicle as the vaporous bubbles which are generated at the bottom of a Kettle of hot water do find a passage through that fluid medium into the ambient Air.
Nor is the skin of animals only thus pervious, but even those of vegetables also seem to be the same; for otherwise I cannot conceive why, if two sprigs of Rosemary (for Instance) be taken as exactly alike in all particulars as can be, and the one be set with the bottom in a Glass of water, and the other be set just without the Glass, but in the Air onely, though you stop the lower end of that in the Air very carefully with Wax, yet shall it presently almost wither, whereas the other that seems to have a supply from the subjacent water by its small pipes, or microscopical pores, preserves its greenness for many days, and sometimes weeks.
Now, this to me, seems not likely to proceed from any other cause then the avolation of the juice through the skin; for by the Wax, all those other pores of the stem are very firmly and closely stop'd up. And from the more or less porousness of the skins or rinds of Vegetables may, perhaps, be somewhat of the reason given, why they keep longer green, or sooner wither; for we may observe by the bladdering and craking of the leaves of Bays, Holly, Laurel, &c. that their skins are very close, and do not suffer so free a passage through them of the included juices.
But of this, and of the Experiment of the Rosemary, I shall elsewhere more fully consider, it seeming to me an extreme luciferous Experiment, such as seems indeed very plainly to prove the Schematism or structure of
Errata
