Chapter 33

CHAP. VIII.Of the Motion of Animals.

Of the Motion of Animals.

Next to the two grand Acts of animal Life, their Sense or Respiration, I shall consider theirMotion, orlocomotive Faculty; whereby they convey themselves from Place to Place, according to their Occasions, and Way of Life: And the admirable Apparatus to this Purpose, is a plain Demonstration of God’s particular Foresight, Care, and especial Providence towards all the animal World.

And here I might view in the first Place the Muscles, their curious Structure[a], the nice tacking them to every Joynt, to pull it this Way, and that Way, and the other Way, according to the special Purpose, Design, and Office of every such Joint: Also their various Size and Strength; somelarge and corpulent, others less, and some scarce visible to the naked Eye; all exactly fitted to every Place, and every use of the Body. And lastly, I might take Notice of the muscular Motions, both involuntary and spontaneous[b].

Next, I might survey the special Fabrick of the Bones[c], ministring to animal Motion. Next, Imight take notice of the Joynts[d], their compleat Form adjusted to the Place, and Office they are employed in; their Bandage, keeping them from Luxations; the oily Matter[e]to lubricatethem, and their own Smoothness to facilitate their Motion.

And lastly, I might trace the various Nerves throughout the Body; sent about to minister to its various Motions[f]. I might consider their Origine[g], their Ramifications to the several Parts, and their Inosculations with one another, according to the Harmony and Accord of one Part with another, necessary for the Benefit of the Animal. But some of those Things I have given some Touches uponalready, and more I shall mention hereafter[h], and it would be tedious here to insist upon them all.

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

And here it is admirable to consider the various Methods of Nature[i], suited to the Occasions of various Animals. In some their Motion is swift, in others slow. In some performed with two, four, or more Legs: in some with two, or four Wings: in some with neither[k].

And first for swift or slow Motion. This we find is proportional to the Occasions of each respective Animal.Reptiles, whose Food, Habitation, and Nests, 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;but their vermicular or sinuous Motion (performed with no less Art, and as curiously provided for as the Legs or Wings of other Creatures: This, I say,) is sufficient for their Conveyance.

ManandBeasts, whose Occasions require a large Room, have accordingly a swifter Motion, with proper Engines for that Service; answerable to their Range for Food, their Occupation of Business, or their want of Armature, and to secure them against Harms[l].

But for the winged Creatures (Birds and Insects,) as they are to traverse large Tracts of Land and Water, for their Food, for their commodious Habitation, or Breeding their Young, to find Places of Retreat and Security from Mischiefs; so they have accordingly the Faculty of flying in the Air; and that swiftly or slowly, a long or short a Time, according to their Occasions and Way of Life. And accordingly their Wings, and whole Body, are curiously prepared for such a Motion; as I intend to shew in a proper Place[m].

Another remarkable Thing in the motive Faculty of all Creatures, is the neat, geometrical Performance of it. The most accurate Mathematician, the most skilful in mechanick Motions, can’t prescribe a nicer Motion (than what they perform) to the Legs and Wings of those that walk or fly[n],or to the Bodies of those that creep[o]. Neither can the Body be more compleatly poised for the Motion it is to have in every Creature, than it already actually is. From the largest Elephant, to the smallest Mite, we find the Body artfully balanced[p]. The Head not too heavy, nor too light for the rest of the Body, nor the rest of the Body for it[q]. TheVisceraare not let loose, or so placed, as to swag, over-balance, or over-set the Body; but well-braced, and distributed to maintain the æquipoise of the Body. The motive Parts also are admirably well fixed in respect to the Center of Gravity; placed in the very Point, fittest to support and convey the Body. Every Leg beareth his true Share of the Body’s Weight. And the Wings so nicely are set to the Center of Gravity, as even in that fluidMedium, the Air, the Body is as truly balanced, as we could have balanced it with the nicest Scales.

But among all Creatures, none more elegant than the sizing the Body ofMan, the gauging his Body so nicely, as to be able to stand erect, tostoop, to sit, and indeed to move any way, only with the Help of so small a Stay as the Feet[r]: whose Mechanism of Bones, Tendons and Muscles to this purpose, is very curious and admirable.

FOOTNOTES:[a]That the Muscles are compounded of Fibres, is visible enough. Which Fibres, the curious and ingeniousBorellisaith, are cylindraceous; not hollow, but filled with a spungy, pithy Substance, after the manner of Elder, as he discovered by his Microscopes.Borel. de Mot. Animal.Part 1. These Fibres, he saith, are naturally white; but derive their Redness only from the Blood in them.These Fibres do in every Muscle, (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 same Way, but some run aslant, some longways,&c.according to the Action or Position of each respective Muscle. The Particulars of which, and of divers other Observables in the Muscles, would, besides Figures, take up too much room in these Notes; and therefore I must refer to the Anatomists, particularlySteno,Borelli,Cowper, &c.[b]The infinite Creator hath generally exerted his Art and Care, in the Provision made by proper Muscles 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, such as of the Heart, Stomach, Guts,&c.are involuntary, the Muscles acting whether we sleep or wake, whether we will or no. And it is no less providential that some, even of the vital Motions, are partly voluntary, partly involuntary, as that for Instance, of Breathing, which is performed both sleeping and waking; but can be intermitted for a short Time on occasion, as for accurate hearing any Thing,&c.or can be encreased by a stronger Blast, 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 such as are voluntary, it is a no less Providence, that they are absolutely under the Power of the Will; so as that the Animal hath it in his Power to command the Muscles and Spirits of any part of its Body, to perform such Motions and Actions as it hath Occasion for.[c]Quid dicam de Ossibus? quæ subjecta corpori mirabiles commissuras habent, & ad stabilitatem aptas, & ad artus finiendos accommodatas, & ad motum, & ad omnem corporis actionem.Cicer. de Nat. Deor. l. 2. c. 55.By Reason it would be endless to mention all the Curiosities observable in the Bones, I shall for a Sample, single out only an Instance or two, to manifest that Design was used in the Structure of these Parts in Man.The first shall be in theBack-Bone, which (among many others) hath these 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 Asperities and Hollows, made for catching and holding; so as firmly to lock and keep the Joynts from Luxations, but withal to afford them such a Motion, as is necessary for the Incurvations of the Body. 2. The difference of its own Joynts in the Neck, Back and Loins. In the Neck, theAtlas, or upperVertebra, as also theDentata, are curiously made, and joynted (differently from the rest) for the commodious and easie bending and turning the Head every way. In theThorax, or Back, the Joynts are more close and firm; and in the Loins, more lax and pliant; as also the Spines are different, and the Knobs and Sockets turned the quite contrary way, to answer the Occasions the Body hath to bend more there, than higher in the Back. I shall close this Remark with the ingenious Dr.Keil’s Observation.The Structure of theSpineis 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, theMedulla Spinalismust have been necessarily bruised at every Angle or Joynt; besides, the whole would not have been so pliable for the several Postures we have occasion to put our selves in. If it had been made of several Bones without intervening Cartilages, we should have had no more Use of it, than if it had been but one Bone. If eachVertebrahad had its own distinct Cartilages, it might have been easilydislocated. And lastly, The oblique Processes of each superior and inferiorVertebra, keep the middle one that it can neither be thrust backwards nor forwards to compress theMedulla Spinalis.Keil’sAnat.c. 5. §. 8.Compare here whatGalensaith of the Articulations, Ligaments, Perforation,&c.of theSpine, to prove the Wisdom and Providence of the Maker of animal Bodies, against such as found fault with Nature’s Works; among which he namesDiagoras,Anaxagoras,AsclepiadesandEpicurus.V.Galen. de Us. Part. L. 12. init.andChap. 11,&c.alsoL. 13. init.2. The next Instance shall be in one or two Things, wherein the Skeletons of Sexes differ. Thus thePelvismade in the Belly by theIlium,Ossa CoxendicisandPubis, is larger in a Female than Male Skeleton, that there may be more room for the lying of theVisceraandFœtus. So the Cartilage bracing together the twoOssa Pubis, orSharebones,Bartholinesaith, is twice thicker and laxer in Women than Men: As also is the Cartilage that tieth theOs Sacrumto itsVertebra; and all to give way to the Passage of theFœtus.Another considerable Difference is in the cartilaginous Production of the seven long Ribs, whereby they are braced to the Breast-Bone. These are harder and firmer in Women than in Men; the better to support the Weight of the Breasts, the sucking Infant,&c.[d]It is remarkable in the Joynts, and a manifest 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 consisting of two large Superficies, Concave and Convex, some furrowed and ridged, some 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 spungy, as their Extremities commonly are, nor hard and brittle, but capped with a strong, tough, smooth, cartilaginous Substance, serving both to Strength and Motion.But let us here take notice of whatGalenmentions on this Subject.Articulorum unusquisque Eminentiam Cavitati immissam habet: Veruntamen hoc fortasse non adeò mirabile est: Sed si, consideratâ omnium totius corporis ossium mutuâ connexione, Eminentias cavitatibus suscipientibus æquales semper inveneris; Hoc mirabile. Si enim justo amplior esset Cavitas, laxus sanè & infirmus fieret Articulus; si strictior, motus difficulter fieret, ut qui nullam versionem haberet; ac periculum esset non parvum, eminintias ossium arctatas frangi: sed horum neutrum factum est.——Sed quoniam ex tam securâ constructione periculum erat, nè motiones difficiliùs fierent, & eminentiæ ossium extererentur, duplex rursus auxilium in id Natura molita est. 1. Cartilagine os utrumque subungens, atque oblinens: alterum, ipsis Cartilaginibus humorem unctuosum, velut oleum, superfundens; per quem facilè mobilis, & attritu contumax omnis articulatio Ossium facta est.——Ut undique diligenter Articulus omnis custodiretur, Ligamenta quædam ex utroque osse produxit Natura.Galen de Us. Part. l. 1. c. 15.[e]For the affording this oily or mucilaginous Matter, there areGlandulesvery commodiously placed near the Joynts, so as not to suffer too great Compression by the Motion of the neighbouring Bones, and yet to receive a due Pressure, so as to cause a sufficient Emission of the Mucilage into the Joynts. Also another Thing considerable is, that the excretory Ducts of themucilaginous Glandshave some Length in their Passage from the Glands to their Mouths; which is a good Contrivance, to prevent their Mouths being oppressed by the Mucilage, as also to hinder the too plentiful Effusion thereof, but yet to afford a due Expressure of it at all Times, and on all Occasions, as particularly in violent and long-continued Motions of the Joynts, when there is a greater than ordinary Expence of it. SeeCowper’sAnat. 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 cut, or straightly bound, that goes to any Muscle, that Muscle shall immediately lose its Motion. Which is doubtless the case of Paralyticks; whose Nerves are some of them by Obstructions, or such like Means, reduced to the same State as if cut or bound.And this also is the cause of thatNumnessorSleepinesswe find oftentimes, by long sitting or lying on any Part.Neither is this a modern Notion only: ForGalensaith,Principium Nervorum omnium Cerebrum est, & spinalis Medulla.——Et Nervi à Cerebro animalem virtutem accipiunt——Nervorum utilitas est facultatem Sensûs & Motûs à principio in partes diducere.And this he intimates to have been the Opinion ofHippocratesandPlato. De Us. Part. l. 1. c. 16.& passim.[g]Dr.Willisthinks, that in theBrainthe Spirits are elaborated that minister to voluntary Motion; but in theCerebellum, such as effect involuntary, or natural Motions; such as that of the Heart, the Lungs,&c.Cerebri Anat.c. 15.[h]SeeBook V. Chap. 8.[i]To the foregoing, I shall briefly add some Examples of the special Provision made for the Motion of some Animals byTemporary Parts.FrogsandToads, in theirTadpole-state, have Tails, which fall off when their Legs are grown out. TheLacerta aquatica, orWater-Newt, when Young, hath four neat ramified Fins, two on a Side, growing out a little above its Fore-Legs, to poise and keep its Body upright, (which gives it the Resemblance of a young Fish,) which fall off when the Legs are grown. And theNymphæandAureliæ, of all or most of the Insects bred in the Waters, as they have particular Forms, different from the Insects they produce; so 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 Insects themselves, in their mature State in the Air.[k]Jam verò alia animalia gradiendo, alia serpendo ad pastum accedunt, alia volando, alia nando.Cic. de Nat. Deor. l. 2. c. 47.Compare also whatGalenexcellently observes concerning the Number of Feet in Man, and in other Animals; and the wise Provision thereby made for the Use and Benefit of the respective Animals.De Us. Part.in the beginning of the third Book.[l]As I shall hereafter shew, that the indulgent Creator hath abundantly provided for the Safety of Animals by their Cloathing, Habitations, Sagacity and Instruments of Defence; so there appears to be a Contemperament of theirMotionwith these Provisions. They that are well armed and guarded, have commonly a slower Motion; whereas they that are destitute thereof, are swifter. So also timid helpless Animals are commonly swift; thus Deer and Hares: But Animals endowed with Courage, Craft, Arms,&c.commonly have a slower Motion.[m]SeeBook VII. Chap. 1.[n]SeeBook VII. Chap. 1.the end.[o]SeeBook IX. Chap. 1. Note (c).[p]Siquis unquam alius Opifex, æqualitatis & proportionis magnam habuit providentiam, certè Natura habuit in animalium corporibus conformandis; unde Hippocrates eam rectissimè justam nominat.Galen. de Us. Part. l. 2. c. 16.[q]The Make of the Bodies of some Water-fowl, seems to contradict what I here say, the Heads and long Necks of some, as of Swans, Ducks and Geese; and the hinder Parts of others, as of the Doucker and More-hen, and some other Kinds, seeming to be too heavy for the rest of their Body. But instead of being an Argument against, it is a notable Instance of, the divine Art and Providence, these Things being nice Accommodations to their way of Life. Of such as have long Necks, seeBook VII. Chap. 2. Note (i).And as for such whose hinder Parts seem to over-balance their foremost Parts, whereby they fly with their Bodies in a manner erect, this also is an excellent Accommodation to their way of Life, which is Diving rather than Flying.Vid.Book VII. Chap. 4. Note (k).[r]SeeBook V. Chap. 2. Note (h).

[a]That the Muscles are compounded of Fibres, is visible enough. Which Fibres, the curious and ingeniousBorellisaith, are cylindraceous; not hollow, but filled with a spungy, pithy Substance, after the manner of Elder, as he discovered by his Microscopes.Borel. de Mot. Animal.Part 1. These Fibres, he saith, are naturally white; but derive their Redness only from the Blood in them.These Fibres do in every Muscle, (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 same Way, but some run aslant, some longways,&c.according to the Action or Position of each respective Muscle. The Particulars of which, and of divers other Observables in the Muscles, would, besides Figures, take up too much room in these Notes; and therefore I must refer to the Anatomists, particularlySteno,Borelli,Cowper, &c.

These Fibres do in every Muscle, (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 same Way, but some run aslant, some longways,&c.according to the Action or Position of each respective Muscle. The Particulars of which, and of divers other Observables in the Muscles, would, besides Figures, take up too much room in these Notes; and therefore I must refer to the Anatomists, particularlySteno,Borelli,Cowper, &c.

[b]The infinite Creator hath generally exerted his Art and Care, in the Provision made by proper Muscles 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, such as of the Heart, Stomach, Guts,&c.are involuntary, the Muscles acting whether we sleep or wake, whether we will or no. And it is no less providential that some, even of the vital Motions, are partly voluntary, partly involuntary, as that for Instance, of Breathing, which is performed both sleeping and waking; but can be intermitted for a short Time on occasion, as for accurate hearing any Thing,&c.or can be encreased by a stronger Blast, 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 such as are voluntary, it is a no less Providence, that they are absolutely under the Power of the Will; so as that the Animal hath it in his Power to command the Muscles and Spirits of any part of its Body, to perform such Motions and Actions as it hath Occasion for.

[c]Quid dicam de Ossibus? quæ subjecta corpori mirabiles commissuras habent, & ad stabilitatem aptas, & ad artus finiendos accommodatas, & ad motum, & ad omnem corporis actionem.Cicer. de Nat. Deor. l. 2. c. 55.By Reason it would be endless to mention all the Curiosities observable in the Bones, I shall for a Sample, single out only an Instance or two, to manifest that Design was used in the Structure of these Parts in Man.The first shall be in theBack-Bone, which (among many others) hath these 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 Asperities and Hollows, made for catching and holding; so as firmly to lock and keep the Joynts from Luxations, but withal to afford them such a Motion, as is necessary for the Incurvations of the Body. 2. The difference of its own Joynts in the Neck, Back and Loins. In the Neck, theAtlas, or upperVertebra, as also theDentata, are curiously made, and joynted (differently from the rest) for the commodious and easie bending and turning the Head every way. In theThorax, or Back, the Joynts are more close and firm; and in the Loins, more lax and pliant; as also the Spines are different, and the Knobs and Sockets turned the quite contrary way, to answer the Occasions the Body hath to bend more there, than higher in the Back. I shall close this Remark with the ingenious Dr.Keil’s Observation.The Structure of theSpineis 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, theMedulla Spinalismust have been necessarily bruised at every Angle or Joynt; besides, the whole would not have been so pliable for the several Postures we have occasion to put our selves in. If it had been made of several Bones without intervening Cartilages, we should have had no more Use of it, than if it had been but one Bone. If eachVertebrahad had its own distinct Cartilages, it might have been easilydislocated. And lastly, The oblique Processes of each superior and inferiorVertebra, keep the middle one that it can neither be thrust backwards nor forwards to compress theMedulla Spinalis.Keil’sAnat.c. 5. §. 8.Compare here whatGalensaith of the Articulations, Ligaments, Perforation,&c.of theSpine, to prove the Wisdom and Providence of the Maker of animal Bodies, against such as found fault with Nature’s Works; among which he namesDiagoras,Anaxagoras,AsclepiadesandEpicurus.V.Galen. de Us. Part. L. 12. init.andChap. 11,&c.alsoL. 13. init.2. The next Instance shall be in one or two Things, wherein the Skeletons of Sexes differ. Thus thePelvismade in the Belly by theIlium,Ossa CoxendicisandPubis, is larger in a Female than Male Skeleton, that there may be more room for the lying of theVisceraandFœtus. So the Cartilage bracing together the twoOssa Pubis, orSharebones,Bartholinesaith, is twice thicker and laxer in Women than Men: As also is the Cartilage that tieth theOs Sacrumto itsVertebra; and all to give way to the Passage of theFœtus.Another considerable Difference is in the cartilaginous Production of the seven long Ribs, whereby they are braced to the Breast-Bone. These are harder and firmer in Women than in Men; the better to support the Weight of the Breasts, the sucking Infant,&c.

By Reason it would be endless to mention all the Curiosities observable in the Bones, I shall for a Sample, single out only an Instance or two, to manifest that Design was used in the Structure of these Parts in Man.

The first shall be in theBack-Bone, which (among many others) hath these 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 Asperities and Hollows, made for catching and holding; so as firmly to lock and keep the Joynts from Luxations, but withal to afford them such a Motion, as is necessary for the Incurvations of the Body. 2. The difference of its own Joynts in the Neck, Back and Loins. In the Neck, theAtlas, or upperVertebra, as also theDentata, are curiously made, and joynted (differently from the rest) for the commodious and easie bending and turning the Head every way. In theThorax, or Back, the Joynts are more close and firm; and in the Loins, more lax and pliant; as also the Spines are different, and the Knobs and Sockets turned the quite contrary way, to answer the Occasions the Body hath to bend more there, than higher in the Back. I shall close this Remark with the ingenious Dr.Keil’s Observation.

The Structure of theSpineis 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, theMedulla Spinalismust have been necessarily bruised at every Angle or Joynt; besides, the whole would not have been so pliable for the several Postures we have occasion to put our selves in. If it had been made of several Bones without intervening Cartilages, we should have had no more Use of it, than if it had been but one Bone. If eachVertebrahad had its own distinct Cartilages, it might have been easilydislocated. And lastly, The oblique Processes of each superior and inferiorVertebra, keep the middle one that it can neither be thrust backwards nor forwards to compress theMedulla Spinalis.Keil’sAnat.c. 5. §. 8.

Compare here whatGalensaith of the Articulations, Ligaments, Perforation,&c.of theSpine, to prove the Wisdom and Providence of the Maker of animal Bodies, against such as found fault with Nature’s Works; among which he namesDiagoras,Anaxagoras,AsclepiadesandEpicurus.V.Galen. de Us. Part. L. 12. init.andChap. 11,&c.alsoL. 13. init.

2. The next Instance shall be in one or two Things, wherein the Skeletons of Sexes differ. Thus thePelvismade in the Belly by theIlium,Ossa CoxendicisandPubis, is larger in a Female than Male Skeleton, that there may be more room for the lying of theVisceraandFœtus. So the Cartilage bracing together the twoOssa Pubis, orSharebones,Bartholinesaith, is twice thicker and laxer in Women than Men: As also is the Cartilage that tieth theOs Sacrumto itsVertebra; and all to give way to the Passage of theFœtus.

Another considerable Difference is in the cartilaginous Production of the seven long Ribs, whereby they are braced to the Breast-Bone. These are harder and firmer in Women than in Men; the better to support the Weight of the Breasts, the sucking Infant,&c.

[d]It is remarkable in the Joynts, and a manifest 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 consisting of two large Superficies, Concave and Convex, some furrowed and ridged, some 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 spungy, as their Extremities commonly are, nor hard and brittle, but capped with a strong, tough, smooth, cartilaginous Substance, serving both to Strength and Motion.But let us here take notice of whatGalenmentions on this Subject.Articulorum unusquisque Eminentiam Cavitati immissam habet: Veruntamen hoc fortasse non adeò mirabile est: Sed si, consideratâ omnium totius corporis ossium mutuâ connexione, Eminentias cavitatibus suscipientibus æquales semper inveneris; Hoc mirabile. Si enim justo amplior esset Cavitas, laxus sanè & infirmus fieret Articulus; si strictior, motus difficulter fieret, ut qui nullam versionem haberet; ac periculum esset non parvum, eminintias ossium arctatas frangi: sed horum neutrum factum est.——Sed quoniam ex tam securâ constructione periculum erat, nè motiones difficiliùs fierent, & eminentiæ ossium extererentur, duplex rursus auxilium in id Natura molita est. 1. Cartilagine os utrumque subungens, atque oblinens: alterum, ipsis Cartilaginibus humorem unctuosum, velut oleum, superfundens; per quem facilè mobilis, & attritu contumax omnis articulatio Ossium facta est.——Ut undique diligenter Articulus omnis custodiretur, Ligamenta quædam ex utroque osse produxit Natura.Galen de Us. Part. l. 1. c. 15.

But let us here take notice of whatGalenmentions on this Subject.Articulorum unusquisque Eminentiam Cavitati immissam habet: Veruntamen hoc fortasse non adeò mirabile est: Sed si, consideratâ omnium totius corporis ossium mutuâ connexione, Eminentias cavitatibus suscipientibus æquales semper inveneris; Hoc mirabile. Si enim justo amplior esset Cavitas, laxus sanè & infirmus fieret Articulus; si strictior, motus difficulter fieret, ut qui nullam versionem haberet; ac periculum esset non parvum, eminintias ossium arctatas frangi: sed horum neutrum factum est.——Sed quoniam ex tam securâ constructione periculum erat, nè motiones difficiliùs fierent, & eminentiæ ossium extererentur, duplex rursus auxilium in id Natura molita est. 1. Cartilagine os utrumque subungens, atque oblinens: alterum, ipsis Cartilaginibus humorem unctuosum, velut oleum, superfundens; per quem facilè mobilis, & attritu contumax omnis articulatio Ossium facta est.——Ut undique diligenter Articulus omnis custodiretur, Ligamenta quædam ex utroque osse produxit Natura.Galen de Us. Part. l. 1. c. 15.

[e]For the affording this oily or mucilaginous Matter, there areGlandulesvery commodiously placed near the Joynts, so as not to suffer too great Compression by the Motion of the neighbouring Bones, and yet to receive a due Pressure, so as to cause a sufficient Emission of the Mucilage into the Joynts. Also another Thing considerable is, that the excretory Ducts of themucilaginous Glandshave some Length in their Passage from the Glands to their Mouths; which is a good Contrivance, to prevent their Mouths being oppressed by the Mucilage, as also to hinder the too plentiful Effusion thereof, but yet to afford a due Expressure of it at all Times, and on all Occasions, as particularly in violent and long-continued Motions of the Joynts, when there is a greater than ordinary Expence of it. SeeCowper’sAnat. 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 cut, or straightly bound, that goes to any Muscle, that Muscle shall immediately lose its Motion. Which is doubtless the case of Paralyticks; whose Nerves are some of them by Obstructions, or such like Means, reduced to the same State as if cut or bound.And this also is the cause of thatNumnessorSleepinesswe find oftentimes, by long sitting or lying on any Part.Neither is this a modern Notion only: ForGalensaith,Principium Nervorum omnium Cerebrum est, & spinalis Medulla.——Et Nervi à Cerebro animalem virtutem accipiunt——Nervorum utilitas est facultatem Sensûs & Motûs à principio in partes diducere.And this he intimates to have been the Opinion ofHippocratesandPlato. De Us. Part. l. 1. c. 16.& passim.

And this also is the cause of thatNumnessorSleepinesswe find oftentimes, by long sitting or lying on any Part.

Neither is this a modern Notion only: ForGalensaith,Principium Nervorum omnium Cerebrum est, & spinalis Medulla.——Et Nervi à Cerebro animalem virtutem accipiunt——Nervorum utilitas est facultatem Sensûs & Motûs à principio in partes diducere.And this he intimates to have been the Opinion ofHippocratesandPlato. De Us. Part. l. 1. c. 16.& passim.

[g]Dr.Willisthinks, that in theBrainthe Spirits are elaborated that minister to voluntary Motion; but in theCerebellum, such as effect involuntary, or natural Motions; such as that of the Heart, the Lungs,&c.Cerebri Anat.c. 15.

[h]SeeBook V. Chap. 8.

[i]To the foregoing, I shall briefly add some Examples of the special Provision made for the Motion of some Animals byTemporary Parts.FrogsandToads, in theirTadpole-state, have Tails, which fall off when their Legs are grown out. TheLacerta aquatica, orWater-Newt, when Young, hath four neat ramified Fins, two on a Side, growing out a little above its Fore-Legs, to poise and keep its Body upright, (which gives it the Resemblance of a young Fish,) which fall off when the Legs are grown. And theNymphæandAureliæ, of all or most of the Insects bred in the Waters, as they have particular Forms, different from the Insects they produce; so 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 Insects themselves, in their mature State in the Air.

[k]Jam verò alia animalia gradiendo, alia serpendo ad pastum accedunt, alia volando, alia nando.Cic. de Nat. Deor. l. 2. c. 47.Compare also whatGalenexcellently observes concerning the Number of Feet in Man, and in other Animals; and the wise Provision thereby made for the Use and Benefit of the respective Animals.De Us. Part.in the beginning of the third Book.

[k]Jam verò alia animalia gradiendo, alia serpendo ad pastum accedunt, alia volando, alia nando.Cic. de Nat. Deor. l. 2. c. 47.

Compare also whatGalenexcellently observes concerning the Number of Feet in Man, and in other Animals; and the wise Provision thereby made for the Use and Benefit of the respective Animals.De Us. Part.in the beginning of the third Book.

[l]As I shall hereafter shew, that the indulgent Creator hath abundantly provided for the Safety of Animals by their Cloathing, Habitations, Sagacity and Instruments of Defence; so there appears to be a Contemperament of theirMotionwith these Provisions. They that are well armed and guarded, have commonly a slower Motion; whereas they that are destitute thereof, are swifter. So also timid helpless Animals are commonly swift; thus Deer and Hares: But Animals endowed with Courage, Craft, Arms,&c.commonly have a slower Motion.

[m]SeeBook VII. Chap. 1.

[n]SeeBook VII. Chap. 1.the end.

[o]SeeBook IX. Chap. 1. Note (c).

[p]Siquis unquam alius Opifex, æqualitatis & proportionis magnam habuit providentiam, certè Natura habuit in animalium corporibus conformandis; unde Hippocrates eam rectissimè justam nominat.Galen. de Us. Part. l. 2. c. 16.

[q]The Make of the Bodies of some Water-fowl, seems to contradict what I here say, the Heads and long Necks of some, as of Swans, Ducks and Geese; and the hinder Parts of others, as of the Doucker and More-hen, and some other Kinds, seeming to be too heavy for the rest of their Body. But instead of being an Argument against, it is a notable Instance of, the divine Art and Providence, these Things being nice Accommodations to their way of Life. Of such as have long Necks, seeBook VII. Chap. 2. Note (i).And as for such whose hinder Parts seem to over-balance their foremost Parts, whereby they fly with their Bodies in a manner erect, this also is an excellent Accommodation to their way of Life, which is Diving rather than Flying.Vid.Book VII. Chap. 4. Note (k).

And as for such whose hinder Parts seem to over-balance their foremost Parts, whereby they fly with their Bodies in a manner erect, this also is an excellent Accommodation to their way of Life, which is Diving rather than Flying.Vid.Book VII. Chap. 4. Note (k).

[r]SeeBook V. Chap. 2. Note (h).

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