large and corpulent, others lefs, and fome scarce vifible to the naked Eye; all exactly fitted to every Place, and every ufe of the Body. And lastly, I might take Notice of the mufcular Motions, both involuntary and spontaneous (b).

Next, I might furvey the fpecial Fabrick of the Bones (c), miniftring to animal Motion. Next, I might

Thefe Fibres, he faith, are naturally white; but derive their Redness only from the Blood in them.

Thefe Fibres do in every Mufcle, (in the Belly at least of the Muscle,) run parallel to one another, in a neat orderly Form. But they do not at all tend the fame Way, but fome run aflant, fome longways, ec. according to the Action or Pofition of each refpective Mufcle. The Particulars of which, and of divers other Obfervables in the Mufcles, would, befides Figures, take up too much room in these Notes; and therefore I muft refer to the Anatomifts, particularly Steno, Borelli, Cowper, &c.

(b) The infinite Creator hath generally exerted his Art and Care, in the Provifion made by proper Mufcles and Nerves, for all the different Motions in animal Bodies, both involuntary, and voluntary. It is a noble Providence that most of the vital Motions, fuch as of the Heart, Stomach, Guts, c. are involuntary, the Mufcles acting whether we fleep or wake, whether we will or no. And it is no lefs providential that fome, even of the vital Motions, are partly voluntary, partly involuntary, as that for Inftance, of Breathing, which is performed both fleeping and waking; but can be intermitted for a fhort Time on occafion, as for accurate hearing any Thing, c. or can be encreafed by a ftronger Blaft, to make the greater Discharges of the Blood from the Lungs, when that any Thing overcharges them. And as for the other Motions of the Body, as of the Limbs, and fuch as are voluntary, it is a no lefs Providence, that they are abfolutely under the Power of the Will; fo as that the Animal hath it in his Power to command the Muscles and Spirits of any part of its Body, to perform fuch Motions and Actions as it hath Occafion for.

(c) Quid dicam de Offibus? que fubjecta corpori mirabiles commiffura: habent, & ad ftabilitatem aptas, & ad artus finiendos accommodatas, & ad motum, & ad omnem corporis actiCicer. de Nat. Deor. 1. 2. c. 55.

onem.

By

By Reafon it would be endlefs to mention all the Curiofities obfervable in the Bones, I fhall for a Sample, fingle out only an Inftance or two, to manifeft that Defign was used in the Structure of thefe Parts in Man.

The firft fhall be in the Back Bone, which (among many others) hath thefe two Things remarkable. 1. Its different Articulations from the other Joynts of the Body. For here most of the Joynts are flat, and withal guarded with Afperities and Hollows, made for catching and holding; fo as firmly to lock and keep the Joynts from Luxations, but withal to afford them fuch a Motion, as is neceffary for the Incurvations of the Body. 2. The difference of its own Joynts

in the Neck, Back and Loins. In the Neck, the Atlas, or upper Vertebra, as alfo the Dentata, are curiously made, and joynted (differently from the reft) for the commodious and eafie bending and turning the Head every way. In the Thorax, or Back, the Joynts are more clofe and firm; and in the Loins, more lax and pliant; as alfo the Spines are different, and the Knobs and Sockets turned the quite contrary way, to answer the Occafions the Body hath to bend more there, than higher in the Back. I fhall close this Remark with the ingenious Dr. Keil's Obfervation.

The Structure of the Spine is the very best that can be contrived; for had it been all Bone, we could have had no Motion in our Backs; had it been of two or three Bones articulated for Motion, the Medulla Spinalis must have been neceffarily bruised at every Angle or Joynt; befides, the whole would not have been fo pliable for the feveral Poftures we have occafion to put our felves in. If it had been made of feveral Bones without intervening Cartilages, we should have had no more Ufe of it, than if it had been but one Bone. If each Vertebra had bad its own diftinét Cartilages, it might have been easily diflocated. And lastly, The oblique Proceffes of each fuperior and inferior Vertebra, keep the middle one that it can neither be thruft backwards nor forwards to compress the Medulla Spinalis. Keil's Anat. c. 5. §. 8.

Compare here what Galen faith of the Articulations, Ligaments, Perforation, c. of the Spine, to prove the Wisdom and Providence of the Maker of animal Bodies, against such as found fault with Nature's Works; among which he names Diagoras, Anaxagoras, Afclepiades and Epicurus. V. Galen.de Uf. Part. L. 12. init. and Chap. II, c. alfo L. 13. init.

2. The next Inftance fhall be in one or two Things, wherein the Skeletons of Sexes differ. Thus the Pelvis made in the Belly by the Ilium, Offa Coxendicis and Pubis, is larger in a Female than Male Skeleton, that there may be more room for the lying of the Vifcera and Fœtus. So the Cartilage bracing together the two Offa Pubis, or Sharebones, Bartholine faith, is twice thicker and laxer in Women than

might take notice of the Joynts (d), their compleat Form adjufted to the Place, and Office they are employed in; their Bandage, keeping them from Luxations; the oily Matter (e) to lubricate them,

Men: As alfo is the Cartilage that tieth the Os Sacrum to its Vertebra; and all to give way to the Paffage of the Fœtus.

Another confiderable Difference is in the cartilaginous Production of the feven long Ribs, whereby they are braced to the Breaft-Bone. These are harder and firmer in Women than in Men; the better to fupport the Weight of the Breafts, the fucking Infant, &c.

(d) It is remarkable in the Joynts, and a manifeft Act of Caution and Design, 1. That altho' the Motion of the Limbs be circular, yet the Center of that Motion is not in a Point, but an ample Superficies. In a Point, the Bones would wear and penetrate one another; the Joynts would be exceedingly weak, c. but the Joynts confifting of two large Superficies, Concave and Convex, fome furrowed and ridged, fome like a Ball and Socket, and all lubricated with an oily Substance, they are incomparably prepared both for Motion and Strength. 2. That the Bones next the Joynt are not fpungy, as their Extremities commonly are, nor hard and brittle, but capped with a ftrong, tough, fmooth, cartilaginous Subitance, ferving both to Strength and Motion.

But let us here take notice of what Galen mentions on this

Subject. Articulorum unufquifque Eminentiam Cavitati immiffam habet: Veruntamen hoc fortaffe non adeò mirabile eft: Sed fi, confideratâ omnium totius corporis offium mutuâ connexione, Eminentias cavitatibus fufcipientibus aquales femper inve neris; Hoc mirabile. Si enim jufto amplior effet Cavitas, laxus fanè infirmus fieret Articulus; fi ftrictior, motus difficulter fieret, ut qui nullam verfionem haberet; ac periculum effet non parvum, eminentias offium arctatas frangi: fed horum neutrum factum eft. Sed quoniam ex tam fecurâ conftructione periculum erat, nè motiones difficiliùs fierent, eminentia offium extererentur, duplex rurfus auxilium in id Natura molita eft. 1. Cartilagine os utrumque fubungens, atque oblinens: alierum, ipfis Cartilaginibus humorem unctuofum, velut oleum, Superfundens; per quem facile mobilis, & attritu contumax omnis articulatio Offium fatta eft. Ut undique diligenter Articulus omnis cuftodiretur, Ligamenta quadam ex utroque offe produxit Natura. Galen de Uf. Part. 1. r. c. 15.

(e) For the affording this oily or mucilaginous Matter, there are Glandules very commodiously placed near the Joynts, M

Book IV. them, and their own Smoothness to facilitate their Motion.

And lastly, I might trace the various Nerves throughout the Body; fent about to minifter to its various Motions (f). I might confider their Origine (g), their Ramifications to the feveral Parts, and their Inofculations with one another, according to the Harmony and Accord of one Part with another, neceffary for the Benefit of the Animal. But fome of thofe Things I have given fome Touches up

fo as not to fuffer too great Compreffion by the Motion of the neighbouring Bones, and yet to receive a due Preffure, fo as to cause a fufficient Emillion of the Mucilage into the Joynts. Allo another Thing confiderable is, that the excretory Ducts of the mucilaginous Glands have fome Length in their Paffage from the Glands to their Mouths; which is a good Contrivance, to prevent their Mouths being oppreffed by the Mucilage, as alfo to hinder the too plentiful Effufion thereof, but yet to afford a due Expreffure of it at all Times, and on all Occafions, as particularly in violent and long-continued Motions of the Joynts, when there is a greater than ordinary Expence of it. See Cowper's Anat. Tab. 79.

(f) There is no doubt to be made, but that the Muscles receive their Motion from the Nerves. For if a Nerve be out, or ftraightly bound, that goes to any Muscle, that Mufcle fhall immediately lofe its Motion. Which is doubtless the cafe of Paralyticks; whofe Nerves are fome of them by Obftructions, or fuch like Means, reduced to the fame State as if cut or bound.

And this alfo is the caufe of that Numnefs or Sleepiness we find oftentimes, by long fitting or lying on any Part.

Neither is this a modern Notion only: For Galen faith, Principium Nervorum omnium Cerebrum eft, & fpinalis Medulla. Et Nervi à Cerebro animalem virtutem accipiunt Nervorum utilitas eft facultatem Sensus & Motûs à principio in partes diducere. And this he intimates to have been the Opinion of Hippocrates and Plato. De Uf. Part. 1. 1. c. 16. paffim.

(g) Dr. Willis thinks, that in the Brain the Spirits are elaborated that minifter to voluntary Motion; but in the Cerebellum, fuch as effect involuntary, or natural Motions; fuch as that of the Heart, the Lungs, &c. Cerebri Anat. C. 15.

on

on already, and more I fhall mention hereafter (b)2 and it would be tedious here to infift upon them all.

I fhall therefore only speak diftinctly to the Locomotive Act it self, or what directly relates to it.

And here it is admirable to confider the various Methods of Nature (i), fuited to the Occafions of various Animals. In fome their Motion is swift, in others flow. In fome performed with two, four, or more Legs: in fome with two, or four Wings: in fome with neither (k).

And firft for fwift or flow Motion. This we find is proportional to the Occafions of each refpective Animal. Reptiles, whofe Food, Habitation, and Nefts, lie in the next Clod, Plant, Tree, or Hole, or can bear long Hunger and Hardship, they need neither Legs nor Wings for their Transportation;

(b) See Book V. Chap. 8.

(i) To the foregoing, I fhall briefly add fome Examples of the special Provifion made for the Motion of fome Animals by Temporary Parts. Frogs and Toads, in their Tadpole-ftate, have Tails, which fall off when their Legs are grown out. The Lacerta aquatica, or Water-Newt, when Young, hath four neat ramified Fins, two on a Side, growing out a little above its Fore-Legs, to poife and keep its Body upright, (which gives it the Refemblance of a young Fish,) which fall off when the Legs are grown. And the Nympha and Aurelia, of all or moft of the Infects bred in the Waters, as they have particular Forms, different from the Infects they produce; fo have also peculiar Parts afforded them for their Motion in the Waters: Oars, Tails, and every Part adapted to the Waters, which are utterly varied in the Infects themfelves, in their mature State in the Air.

(k) Fam verò alia animalia gradiendo, alia ferpendo ad paftum accedunt, alia volando, alia nando. Cic. de Nat. Deor. 1. 2. c. 47.

Compare alfo what Galen excellently obferves concerning the Number of Feet in Man, and in other Animals; and the wife Provifion thereby made for the Ufe and Benefit of the refpective Animals. De U. Part. in the beginning of the third Book.