CHAP. II.
Of the Head, Stomach, and other Parts of Birds.
Thus having dispatched the Parts principally concerned in the Motion of the Feather’d Tribe, let us proceed to some other Parts not yet animadverted upon. And we will begin with the Head, concerning which I have already taken notice of its Shape for making way through the Air; of the make of the Bill, for gathering Food, and other Uses; the commodious Situation of the Eye; and I might add that of the Ear too, which would be in the way, and obstruct Flight, if ’twas like that of most other Animals: Also I might say a great deal of the Conformation of the Brain, and of the Parts therein wanting, and of others added, like to what is observable in Fishes; whose Posture in the Waters resembles that of Birds in the Air[a], and both very different from Man and Beasts; and lastly, to hint at no more, I might survey the peculiar Structure of the Larynx[b], the Tongue[c], the inner Ear[d], and many Matters besides; but for a Sample, I shall only insist upon the wonderful Provision in the Bill for the judging of the Food, and that is by peculiar Nerves lodged therein for that Purpose; small and less numerous in such as have the Assistance of another Sense, the Eye; but large, more numerous, and thickly branched about, to the very End of the Beak, in such as hunt for their Food out of Sight in the Waters, in Mud, or under Ground[e].
And now from the Head and Mouth, pass we to its near Ally, the Stomach, another no less notable than useful Part; whether we consider the Elegancy of its Fibres and Muscles, or its Multiplicity; one to soften and macerate, another to digest; or its Variety, suited to various Foods, some membraneous, agreeable to the frugivorous, or carnivorous Kind; same musculous and strong[f], suited to the Comminution, and grinding of Corn and Grain, and so to supply the Defect of Teeth.
And now to this Specimen of the Parts, I might add many other Things, no less curiously contriv’d, made and suited to the Occasions of these Volatiles; as particularly the Stratum and Lodgment of the Lungs[g]; the Configuration of the Breast, and its Bone, made like a Keel, for commodious Passage through the Air, to bear the large and strong Muscles, which move the Wings, and to counterpoise the Body, and support and rest it upon at roost. The Neck also might deserve our Notice, always either exactly proportion’d to the Length of the Legs, or else longer, to hunt out Food, to search in the Waters[h]; as also to counterpoise the Body in Flight[i]. And lastly, I might here take Notice of the Defect of the Diaphragm, so necessary in other Animals to Respiration; and also of divers other Parts redundant, defective, or varying from other Animals. But it would be tedious to insist upon all; and therefore to the Examples already given, I would rather recommend a nice Inspection[k], of those curious Works of God, which would be manifest Demonstrations of the admirable Contrivance and Oeconomy of the Bodies of those Creatures.
From the Fabrick therefore of their Bodies, I shall pass to a Glance of one or two Things, relating to their State; and so conclude this Genus of the animal World.
FOOTNOTES:
[a] Cerebra Hominum & Quadrupedum in plerisque similia existunt——Capitibus Volucrum & Piscium contenta, ab utrisque prioribus longè diversa, tamen inter se, quoad præcipuas ἐγκεφάλου partes, Symbola reperiuntur. The Particulars wherein the Brains of Birds and Fishes agree with one another, and wherein they differ from the Brain of Man and Beasts, see in the same justly famous Author, Willis Cereb. Anat. c. 5.
[b] Circa bifurcationem Asperæ Arteriæ, elegans Artificis liberè agentis indicium detegitur ex Avium comparatione cum Quadrupedibus: cùm Vocis gratia in diversis Avibus diversam musculorum fabricam bifurcationi Asperæ Arteriæ dederit, quorum nullum vestigium extat in Homine & Quadrupedibus mihi visis, ubi omnes vocis musculos capiti Arteriæ junxit. In Aquilâ, &c. supra bifurcationem, &c. Steno in Blas. Anat. Animal. P. 2. c. 4.
The Aspera Arteria is very remarkable in the Swan, which is thus described by T. Bartholin, viz. Aspera Arteria admirandæ satìs structuræ. Nam pro Colli longitudine deorsum Oesophagi comes protenditur donec ad sternum perveniat, in cujus capsulam se incurvo flexu insinuat & recondit, velut in tuto loco & thecâ, moxque ad fundum ejusdem cavitatis delata sursum reflectitur, egrediturque angustias Sterni, & Claviculis mediis concensis, quibus ut fulcro nititur, ad Thoracem se flectit——Miranda hercle modis omnibus constitutio & Respriationi inservit & Voci. Nam cùm in stagnorum fundo edulia pro victu quærat, longissimo indiguis collo, ne longa mora suffocationis incurreret periculum. Et certè dum dimidiam fere horam toto Capite & Collo pronis vado immergitur, pedibus in altum elatis cœloque obversis, ex eâ Arteriæ quæ pectoris dictæ vaginæ reclusa est portione, tanquam ex condo promo spiritum haurit. Blas. ib. c. 10.
[c] The Structure of the Tongue of the Wood-Pecker is very singular and remarkable, whether we look at its great Length, its Bones and Muscles, its encompassing part of the Neck and Head, the better to exert it self in Length; and again, to retract it into its Cell; and lastly, whether we look at its sharp, horny, bearded Point, and the glewy Matter at the end of it, the better to stab, to stick unto, and draw out little Maggots out of Wood. Utilis enim Picis (saith Coiter) ad Vermiculos, Formicas, aliaque Insectæ venanda talis Lingua foret. Siquidem Picus, innata suâ sagacitate cùm deprehendit alibi in arboribus, vel carie, vel aliâ de causâ cavatis, Vermes insectaque delitescere, ad illas volitat, seseque digitis, ungulisque posterioribus robustissimis, & Caudæ pennis rigidissimis sustentat, donec valido ac peracuto Rostro arborent pertundat; arbore pertusâ, foramini rostrum immittit, ac quo animacula stridore excitet percellatque, magnam in arboris cavo emittit vocem, insecta vociferatione hâc concitata huc illucque repunt; Picus v. linguam suam exerit, atque aculeis, hamisque animalia infigit, infixa attrahit & devorat. Vid. Blasii ubi supra. P. 2. c. 24.
[d] I have before, in Book IV. Chap. 3. Note (u), taken notice of what others have observed concerning the inner Ear of Birds, reserving my own Observations for this Place: Which I hope may be acceptable, not only for being some of them new, but also shewing the Mechanism of Hearing in general.
In this Organ of Birds, I shall take notice only of three Parts, the Membranes and Cartilages; the Columella; and the Conclave: The Drum, as some call it, or Membrana Tympani, as others, consists of two Membranes, the Outer, which covers the whole Meatus, Bason or Drum, (as some call it) and the inner Membrane. To support, distend and relax the outermost, there is one single Cartilage, reaching from the Side of the Meatus, to near the middle of the Membrane. On the top of the Columella is another Cartilage, consisting of three Branches, a.b.c. in Fig. 23. The longest middle Branch a. is joined to the top of the single upper Cartilage before spoken of, and assists it to bear up the upper outer Membrane: The two Branches, b.c. are joined to the Os Petrosum, at some distance from the outer Membrane: Upon this inner Cartilage, is the inner Membrane fixed, the two outer Sides of which, a.b. and a.c. are joined to the outer Membrane, and make a kind of three-square Bag. The Design of the two Branches or Legs of the Cartilage, b.c. are I conceive to keep the Cartilage and Columella from wavering side-ways, and to hinder them from flying too much back: There is a very fine slender Ligament extended from the opposite side, quite cross the Meatus or Bason, to the Bottom of the Cartilage, near its joining to the Columella. Thus much for the Membranæ Tympani, and their Cartilages.
The next Part is the Columella (as Schelhammer calls it.) This is a very fine, thin, light, bony Tube; the Bottom of which spreads about, and gives it the Resemblance of a wooden Pot-lid, such as I have seen in Country-Houses. It exactly shuts into, and covers a Foramen of the Conclave, to which it is braced all round, with a fine subtile Membrane, composed of the tender Auditory Nerve. This Bottom or Base of the Columella, I call the Operculum.
The last Part, which some call the Labyrinth and Cochlea, consisting of Branches more like the Canalos Semicirculares in Man, than the Cochlea, I call the Conclave Auditûs. It is (at in most other Animals) made of hard context Bone. In most of the Birds I have opened, there are circular Canals, some larger, some lesser, crossing one another at right Angles, which open into the Conclave. But in the Goose it is otherwise, there being cochleous Canals, but not like those of other Birds. In the Conclave, at the Side opposite to the Operculum, the tender Part of the Auditory Nerve enters, and lineth all those inner retired Parts, viz. the Conclave and Canals.
As to the Passages, Columnæ, and other Parts observable in the Ear of Birds, I shall pass them by, it being sufficient to my Purpose, to have described the Parts principally concerned in the Act of Hearing. And as the Ear is in Birds the most simple and incomplex of any Animals Ear; so we may from it make an easy and rational Judgment, how Hearing is performed, viz. Sound being a Tremor, or Undulation in the Air, caused by the Collision of Bodies, doth as it moves along, strike upon the Drum, or Membrana Tympani of the Ear: Which Motion, whether strong or languid, shrill or soft, tuneful or not, is at the same Instant impressed upon the Cartilages, Columella, and Operculum, and so communicated to the Auditory Nerve in the Conclave.
And now if we compare the Organ and Act of Hearing, with those of Sight, we shall find, that the Conclave is to Hearing, as the Retina is to Sight; that sonorous Bodies make their Impressions thereby on the Brain, as visible Objects do by the Retina. Also, that as there is an Apparatus in the Eye, by the opening and shutting of the Pupil, to make it correspond to all the Degrees of Light, so there is in the Ear to make it conformable to all the Degrees of Sound, a noble Train of little Bones and Muscles in Man, &c. to strain and relax the Membrane, and at the same Time to open and shut the Basis of the Stapes (the same as what I call the Operculum in Birds:) But in Birds, there is a more simple, but sufficient Apparatus for this Purpose, tender Cartilages, instead of Bones and Joints, to correspond to the various Impressions of Sounds, and to open and shut the Operculum. Besides which, I suspect the Ligament I mentioned, is only the Tendon of a Muscle, reaching to the inner Membrana Tympani, and joined thereto (as I find by a stricter Scrutiny) and not to the Cartilage, as I imagined. By this Muscle, the inner Membrane, and by Means of that the Outer also can be distended or relaxed, as it is in Man, by the Malleus and its Muscle, &c.
[e] Flat-billed Birds, that grope for their Meat, have three Pair of Nerves, that come into their Bills, whereby they have that Accuracy to distinguish what is proper for Food, and what to be rejected by their Taste, when they do not see it. This was most evident in a Duck’s Bill and Head; a Duck having larger Nerves that come into their Bills than Geese, or any other Bird that I have seen; and therefore quaffer and grope out their Meat the most. But then I discovered none of these Nerves in round-bill’d Birds. But since, in my Anatomies in the Country, in a Rook, I first observed two Nerves that came down betwixt the Eyes into the upper Bill, but considerably smaller than any of the three Pair of Nerves, in the Bills of Ducks, but larger than the Nerves in any other round-bill’d Birds. And ’tis remarkable that these Birds, more than any other round-bill’d Birds, seem to grope for their Meat in Cow-dung, &c. Mr. J. Clayton, in Philos. Transact. Nᵒ. 206.
I observ’d three Pair of Nerves in all the broad-bill’d Birds that I could meet with, and in all such at feel for their Food out of Sight, as Snipes, Woodcocks, Curlews, Geese, Ducks, Teals, Widgeons, &c. These Nerves are very large, equalling almost the Optic Nerve in Thickness.——Two are distributed nigh the End of the upper Bill, and are there very much expanded, passing through the Bone into the Membrane, lining the Roof of the Mouth. Dr. A. Moulen. Ibid. Nᵒ. 199. Or both in Mr. Lowthorp’s Abridg. V. 2. p. 861, 862.
[f] The Gizzard is not only made very strong, especially in the Granivorous; but hath also a Faculty of Grinding what is therein. For which Purpose, the Bird swalloweth rough Stones down, which, when grown smooth, are rejected and cast out of the Stomach, as useless. This Grinding may be heard in Falcons, Eagles, &c. by laying the Ear close to them, when their Stomachs are empty, as the famous Dr. Harvey saith. De Generat. Exer. 7.
As to the Strength of the Gizzard, and the Use of Stones to the Digestion of Fowls, divers curious Experiments may be met with, try’d by Seigneur Redi, with glass Bubbles, solid Glass, Diamonds, and other hard Bodies. See his Exp. Nat.
[g] It is no less remarkable in Birds, that their Lungs adhere to the Thorax, and have but little play, than that to other Animals they are loose, and play much, which is a good Provision for their steady Flight. Also they want the Diaphragm, and instead thereof, have divers large Bladders made of thin transparent Membranes, with pretty large Holes out of one into the other. These Membranes seem to me to serve for Ligaments, or Braces to the Viscera, as well as to contain Air. Towards the upper Part, each Lobe of the Lungs is perforated in two Places, with large Perforations; whereof one is towards the outer, the other towards the inner Part of the Lobe. Through these Perforations, the Air hath a Passage into the Belly, (as in Book I. Chap. 1. Note (b);) that is, into the foremention’d Bladders; so that by blowing into the aspera Arteria, the Lungs will be a little rais’d, and the whole Belly blown up, so as to be very turgid. Which doubtless is a Means to make their Bodies more or less buoyant, according as they take in more or less Air, to facilitate thereby, their Ascents, and Descents: Like as it is in the Air-bladders of Fishes, in the last cited Place. Note (i).
[h] Such Birds as have long Legs, have also a long Neck; for that otherwise they could not commodiously gather up their Food, either on Land, or in the Water. But on the other Side, those which have long Necks, have not always long Legs, as in Swans——whose Necks serve them to reach to the Bottom of Rivers, &c. Willughby’s Ornithol. L. 1. c. 1. §. 7.
[i] We have sufficient Instances of this in Geese, Ducks, &c. whose Wings, (their Bodies being made for the Convenience of Swimming,) are plac’d out of the Center of Gravity, nearer the Head. But the extending the Neck and Heads in Flight, causeth a due Æquipoise and Libration of the Body upon the Wing. Which is another excellent Use of the long Necks of these Birds, besides that of reaching and searching in the Waters for their Food.
But in the Heron, whose Head and long Neck, (although tuck’d up in Flight,) over-balance the hinder Part of the Body; the long Legs are extended in Flight, to counterpoise the Body, as well as to supply what is wanting in the Tail, from the Shortness of it.
[k] Steno thus Concludes his Myology of the Eagle, Imperfecta hæc Musculorum descriptio, non minùs arida est Legentibus, quàm Inspectantibus fuerit jucunda eorundem præparatio. Elegantissima enim Mechanices artificia, creberrimè in illis obvia, verbis non nisi obscure exprimuntur, carnium autem ductu, tendinum colore, insertionum proportione, & trochlearam distributione oculis exposita omnem superant admirationem. Steno in Blas. Anat. Animal. P. 2. c. 4.