Mikrokosmographia a description of the body of man. Together vvith the controuersies thereto belonging. Collected and translated out of all the best authors of anatomy, especially out of Gasper Bauhinus and Andreas Laurentius. By Helkiah Crooke Doctor of Physicke, physitian to His Maiestie, and his Highnesse professor in anatomy and chyrurgerie. Published by the Kings Maiesties especiall direction and warrant according to the first integrity, as it was originally written by the author.

CHAP. VIII. Of the Cobweb or Membrane of the Cristalline humor. Of the Membrane which compasseth the glassy humor, and that coat called Retina, or The Net.

THE Membrane which immediately compasseth the Cristalline humour is called in Greeke 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, Aranei-formis, that is the Cobweb, most pro∣perly is it called Cristalloides from the humour whose proper coate it is, yea * 1.1 the verie superficies of the same. Some call it the Looking-glasse, beecause it is bright and translucid. Some thinke it hath his originall from the Pia Mater, and of that opinion is Columbus. Others from the coate called Retina or the net as Aquapendens, but Archangelus conceiueth that it is made of the Opticke-Nerue dila∣ted and drawne out into a wonderfull thinnesse. But wee are of opinion saith Bauhine, that it is engendred in the first conformation, together with the Cristaline humor which * 1.2 is framed of the purest and brightest portion of the seed. It is a Membrane most thinne (so saith Hippocrates in his Booke de Locis in homine) very fast, most light, white, bright and shining beyond measure, the better to admit the light and to be changed thereby, (for onely this Membrane dooth indeede receiue and apprehend the affections of the light) and least if it had bene thicke it should haue hindred the sight.

The substance of it is much like the inward skinne of an Onion or rather like a spiders Cobweb, for the finenesse I meane, and not for the density or fastnesse thereof. This Membrane couereth the cristalline humor both on the foreside and the backside imme∣diately * 1.3 compassing and establishing the same. Although I know that Galen in the sixte chapter of his tenth booke De vsu partium writeth, that it inuesteth this humour onelie there where it toucheth the grapie Membrane, with whom Archangelus also agreeth. But that the whole cristalline humor might be more fit for sensation, it was necessary that it should be compassed round with this Membrane, which notwithstanding we acknow∣ledge to bee thicker, faster and stronger on the fore-side. For because wee see be∣fore vs therefore the faculty and power of this sense ought there to bee more vigo∣rous, * 1.4 because in that place the light is more stronglye vnited by the roundnesse of the Cristalline and the refraction of the watery humors. And therefore Ruffus calleth it Visio & Pupilla, the sight or Apple of the eye. And because in this as it were in a glasse the Essi∣gies or Image of the Pupilla doth consist, therfore Galen in the place next before quoated, calleth it the Idoll or Image of the sight. On the contrary the backpart of it is looser, thin∣ner and more rare.

If this Membrane be taken away, the figure of the Cristalline humor is destroyed; for * 1.5 whereas before it was smooth, equall and polished; nowe it falleth assunder and becom∣meth vnequall not being able to stand togither when the bande which conteyned it is re∣mooued. In a word, the cristalline humor receyueth from this Membrane not onelie his sensatiue power, nor the forme and figure of his substance, but also his efficacy and virtue. Veynes it hath none, but seemeth to be nourished by the Ciliar Ligament.

The coate of the glassy humor is called 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, which Columbus & Archangelus haue * 1.6 confounded with the cobweb before described. But the trueth is, that their substaunce is different, for this is thinner then the former and encircleth the glassy humor round about least it should either be diffluent or confounded with the watery humour. Other Anato∣mists haue altogether pretermitted the mention thereof, because they think that both hu∣mors are involued by the Cobweb Membrane. In the middest of this coate doth the Cili∣ar or hairy Ligament appeare.

The last Membrane or coate of the eye is called Retina or Reti-formis, [Tab. 3. fig. 8] in Greeke 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, because it resembleth a little round casting Net. This Membrane * 1.7 ariseth from a part of the Braine descending thorough the Opticke Nerue, or if you vvill, from the marrow of the Nerue it selfe as soone as the Nerue attaineth to the eye, and so hangeth at the very roote of the Nerue, from thence it passeth on to the middle of the eie

eye, and within the cauity of the grapy membrane vpon which it immediatly lieth, but is not tied thereto. It is inlarged and like a net or caule compasseth the glassy humour, but without any connexion at all, Aquapendens saith, it is inserted into the vtmost circle of the Cristalline humour, and that by the meanes hereof the Cristalline swimmeth in the midst * 1.8 of the glassy humour as a peece of wood swimmeth in the water. It is soft, reddish, of a mucous substance, not solid and crasse as is the substance of the braine.

Wherefore, neither in substance nor in colour is it like a Membrane, and therefore Galen in the second chapter of his tenth booke de vsu partium saith, it neither deserueth the name of a membrane nor of a coate, for if you separate it from both the humours and lay it vpon a heape by it selfe, [Tab. 3. fig. 8. l.] it will seeme to you to be a part of the brain dilated, and therefore Galen calleth it the net like body; Vessalius saith it can haue no fitter * 1.9 name then the name of a coate, albeit Columbus and Platerus are not of his opinion. Veins and Arteries it hath very many and conspicuous; and indeed more (though they be small) * 1.10 then seeme conuenient for the proportion thereof: for all nerues being inuested with a portion of the Pia mater wherein veines and arteries doe run, this also receiueth a veine & an arterie diuersly branched, wherby Nature hath prouided and prepared aliment not onely for the Nerue, but also for the humours of the eye. In these vessels therefore is blood contained, not thicke not f••culent but thin and fluide, whereby the glassie and Cristalline humours might bee nourished, which because they are pure bodyes do also stand in need of pure blood.

It is also darke and corpulent not translucent, that it might not bee affected or changed by the light.

The first and greatest vse of this Net-like coate is, saith Galen in the second chapter of tenth booke de vsu partium, that when the Cristalline is altered, it might apprehend the * 1.11 Sensation; or rather to leade along the faculty of sensation to the Cristalline humour, be∣cause as we said euen now, it ariseth from the substance of the nerue.

Another vse of it is, that the visiue spirits might bee diffused through the Cristalline humour and the whole eye; to perceiue the alterations of the Cristalline and to transport the images of visible things to the braine as to a iudge.

Finally, whereas it intercedeth betweene the Grapy membrane and the glassy humor it keepeth the pure substance of the glassy humor from being defiled with the blackenesse of the Grapy membrane. And so much concerning the membranes or coates of the eye. Now we proceed vnto the humours.

Notes

• * 1.1

  The Cobweb or coat of the cristalline hu∣mor.
• * 1.2

  Diuers opini∣ons of his O∣riginall.
• * 1.3

  The substance of it.
• * 1.4

  Why ••••••cker before.
• * 1.5

  The vse of it.
• * 1.6

  The coate of the glassy hu∣mor.
• * 1.7

  The Net.
• * 1.8

  The substance thereof.
• * 1.9

  The vessels thereof.
• * 1.10

  The proui∣dence of na∣ture.
• * 1.11

  The vses of it