A Sponge is commonly reckon’d among the Zoophyts, or Plant Animals; and the texture of it, which the Microscope discovers, seems to confirm it; for it is of a form whereof I never observ’d any other Vegetable, and indeed, it seems impossible that any should be of it, for it consists of an infinite number of small short fibres, or nervous parts, much of the same bigness, curiously jointed or contex’d together in the form of a Net, as is more plainly manifest by the little Draught which I have added, in the third Figure of the IX. Scheme, of a piece of it, which [Schem. 9.]
Fig. 3. you may perceive represents a confus’d heap of the fibrous parts curiously jointed and implicated. The joints are, for the most part, where three fibres onely meet, for I have very seldom met with any that had four.

At these joints there is no one of the three that seems to be the stock whereon the other grow, but each of the fibres are, for the most part, of an equal bigness, and seem each of them to have an equal share in the joint; the fibres are all of them much about the same bigness, not smaller towards the top of the Sponge, and bigger neerer the bottom or root, as is usuall in Plants, the length of each between the joints, is very irregular and different; the distance between some two joints, being ten or twelve times more then between some others.

Nor are the joints regular, and of an equitriagonal Figure, but, for the most part, the three fibres so meet, that they compose three angles very differing all of them from one another.

The meshes likewise, and holes of this reticulated body, are not less various and irregular: some bilateral, others trilateral, and quadrilateral Figures; nay, I have observ’d some meshes to have 5, 6, 7, 8, or 9. sides, and some to have onely one, so exceeding various is the Lusus Naturæ in this body.

As to the outward appearance of this Vegetative body, they are so usuall everywhere, that I need not describe them, consisting of a soft and porous substance, representing a Lock, sometimes a fleece of Wool; but it has besides these small microscopical pores which lie between the fibres, a multitude of round pores or holes, which, from the top of it, pierce into the body, and sometimes go quite through to the bottom.

I have observ’d many of these Sponges, to have included likewise in the midst of their fibrous contextures, pretty large friable stones, which must either have been inclos’d whil’st this Vegetable was in formation, or generated in those places after it was perfectly shap’d. The later of which seems the more improbable, because I did not find that any of these stony substances were perforated with the fibres of the Sponge.

I have never seen nor been enform’d of the true manner of the growing of Sponges on the Rock; whether they are found to increase from little to great, like Vegetables, that is, part after part, or like Animals, all parts equally growing together; or whether they be matrices or feed-baggs of any kind of Fishes, or some kind of watry Insect; or whether they are at any times more soft and tender, or of another nature and texture, which things, if I knew how, I should much desire to be informed of: but from a cursory view that I at first made with my Microscope, and some other trials, I supposed it to be some Animal substance cast out, and fastned upon the Rocks in the form of a froth, or congeries of bubbles, like that which I have often observ’d on Rosemary, and other Plants (wherein is included a little Insect) that all the little films which divide these bubbles one from another, did presently, almost after the substance began to grow a little harder, break, and leave onely the thread behind, which might be, as ’twere, the angle or thread between the bubbles, that the great holes or pores observable in these Sponges were made by the eruption of the included Heterogeneous substance (whether air, or some other body, for many other fluid bodies will do the same thing) which breaking out of the lesser, were collected into very large bubbles, and so might make their way out of the Sponge, and in their passage might leave a round cavity; and if it were large, might carry up with it the adjacent bubbles, which may be perceiv’d at the outside of the Sponge, if it be first throughly wetted, and sufferr’d to plump itself into its natural form, or be then wrung dry, and suffer’d to expand it self again, which it will freely do whil’st moist: for when it has thus plump’d it self into its natural shape and dimensions, ’tis obvious enough that the mouths of the larger holes have a kind of lip or rising round about them, but the other smaller pores have little or none. It may further be found, that each of these great pores has many other small pores below, that are united unto it, and help to constitute it, almost like so many rivulets or small streams that contribute to the maintenance of a large River. Nor from this Hypothesis would it have been difficult to explicate, how those little branches of Coral, smal Stones, shells, and the like, come to be included by these frothy bodies: But this indeed was but a conjecture; and upon a more accurate enquiry into the form of it with the Microscope, it seems not to be the true origine of them; for whereas Sponges have onely three arms which join together at each knot, if they had been generated from bubbles they must have had four.

But that they are Animal Substances, the Chymical examination of them seems to manifest, they affording a volatil Salt and spirit, like Harts-Horn, as does also their great strength and toughness, and their smell when burn’d in the Fire or a Candle, which has a kind of fleshy sent, not much unlike to hair. And having since examin’d several Authors concerning them, among others; I find this account given by Bellonius, in the XI. Chap. of his 2d Book, De Aquatilibus. Spongiæ recentes, says he, à siccis longe diversæ, scopulis aquæ marinæ ad duos vel tres cubitos, nonnunquam quatuor tantum digitos immersis, ut fungi arboribus adhærent, sordido quodam succo aut mucosa potius sanie ræfertæ, usque adeò fœtida, ut vel eminus nauseam excitet, continetur autem iis cavernis, quas inanes in siccis & lotis Spongiis cernimus: Putris pulmonis modo nigræ conspiciuntur, verùm quæ in sublimi aquæ nascuntur multo magis opaca nigredine suffusæ sunt. Vivere quidem Spongias adhærendo Aristoteles censet: absolute vero minime: sensumque aliquem habere, vel eo argumento (inquit) credantur, quod difficillime abstrahantur, nisi clanculum agatur: Atq; ad avulsoris accessum ita contrahantur, ut eas evellere difficile sit, quod idem etiam faciunt quoties flatus tempestatésque urgent. Puto autem illis succum sordidum quem supra diximus carnis loco à natura attributum fuisse: atque meatibus latioribus tanquam intestinis aut interaneis uti. Cæterum pars ea quæ Spongiæ cautibus adhærent est tanquam folii petiolus, à quo veluti collum quoddam gracile incipit: quod deinde in latitudinem diffusum capitis globum facit. Recentibus nihil est fistulosum, hæsitantque tanquam radicibus. Superne omnes propemodum meatus concreti latent: inferne verò quaterni aut quini patent, per quos eas sugere existimamus. From which Description, they seem to be a kind of Plant-Animal that adheres to a Rock, and these small fibres or threads which we have described, seem to have been the Vessels which (’tis very probable) were very much bigger whil’st the Interstitia were fill’d (as he affirms) with a mucous, pulpy or fleshy substance; but upon the drying were shrunk into the bigness they now appear.

The texture of it is such, that I have not yet met with any other body in the world that has the like, but onely one of a larger sort of Sponge (which is preserv’d in the Museum Harveanum belonging to the most Illustrious and most learned Society of the Physicians of London) which is of a horney, or rather of a petrify’d substance. And of this indeed, the texture and make is exactly the same with common Sponges, but onely that both the holes and the fibres, or texture of it is exceedingly much bigger, for some of the holes were above an Inch and half over, and the fibres and texture of it was bigg enough to be distinguished easily with ones eye, but conspicuously with an ordinary single Microscope. And these indeed, seem’d to have been the habitation of some Animal; and examining Aristotle, I find a very consonant account hereunto, namely, that he had known a certain little Animal, call’d Pinnothera, like a Spider, to be bred in those caverns of a Sponge, from within which, by opening and closing those holes, he insnares and catches the little Fishes; and in another place he says, That ’tis very confidently reported, that there are certain Moths or Worms that reside in the cavities of a Sponge, and are there nourished: Notwithstanding all which Histories, I think it well worth the enquiring into the History and nature of a Sponge, it seeming to promise some information of the Vessels in Animal substances, which (by reason of the solidity of the interserted flesh that is not easily remov’d, without destroying also those interspers’d Vessels) are hitherto undiscover’d; whereas here in a Sponge, the Parenchyma, it seems, is but a kind of mucous gelly, which is very easily and clearly wash’d away.

The reason that makes me imagine, that there may probably be some such texture in Animal substances, is, that examining the texture of the filaments of tann’d Leather, I find it to be much of the same nature and strength of a Sponge; and with my Microscope, I have observ’d many such joints and knobs, as I have described in Sponges, the fibres also in the hollow of several sorts of Bones, after the Marrow has been remov’d, I have found somewhat to resemble this texture, though, I confess, I never yet found any texture exactly the same, nor any for curiosity comparable to it.