eyes in their breast; and when it is said by Solomon, "A wise man's eyes are in his head," it is to be taken in a second sense, and affordeth no objection. True it is, that the eyes of animals are seated with some difference, but in sanguineous animals in the head, and that more forward than the ear or hole of hearing. In quadrupeds, in regard of the figure of their heads, they are placed at some distance; in latirostrous and flat-billed birds they are more laterally seated; and therefore, when they look intently they turn one eye upon the object; and can convert their heads to see before and behind, and to behold two opposite points at once. But at a more easy distance are they situated in man, and in the same circumference with the ear; for if one foot of the compass be placed upon the crown, a circle described thereby will intersect, or pass over both the ears.

The error in this conceit consists in the ignorance of these cavities, and their proper use in nature; for this is a particular disposure of parts, and a peculiar conformation whereby these holes and sluices supply the defect of gills, and are assisted by the conduit in the head; for, like cetaceous animals and whales, the lamprey hath a fistula, spout or pipe at the back part of the head, whereat it spurts out water. Nor is it only singular in this formation, but also in many other; as in defect of bones, whereof it hath not one, and for the spine or backbone, a cartilaginous substance without any spondyles, processes, or protuberance whatsoever. As also in the provision which nature hath made for the heart; which in this animal is very strangely secured, and lies immured in a cartilage or gristly substance. And lastly, in the colour of the liver; which is in the male of an excellent grass-green, but of a deeper colour in the female, and will communicate a fresh and durable verdure.

CHAPTER XX.

That Snails have two eyes.

WHETHER snails have eyes some learned men have doubted.2 For Scaliger terms them but imitations of eyes, and Aristotle upon consequence denieth them, when he affirms that testaceous animals have no eyes.3 But this now seems sufficiently asserted by the help of exquisite glasses, which discover those black and atramentous spots or globules to be their eyes.4

2 Whether snails, &c.] The snayle hath but 3 senses, that is, the touch, the smell, and the tast; he sees not, he hears not. The touch

is principally in his hornes; the smel and taste in his mouth, in which I found he hath a little black toung not bigger then a hair, with which he frets herbes, bread, and all things that he fastens upon for foode, as I once made a visible and certaine experiment.—Br.

3 Aristotle, &c.] Mr. E. W. Brayley, jun., in a very elaborate and highly interesting paper, in the second volume of the Zoological Journal, has very successfully advocated this opinion of the great father of zoology; and after detailing the various opinions (or rather enquiries) of the most able modern naturalists, he concludes by stating his opinion that Aristotle was right in believing that all the testaceous molusca are without the organ and sense of sight, and that the feelers of snails are only organs endued with the most delicate sense of touch and feeling. In a note, however, Mr. Brayley suggests that as they are certainly capable of conveying to the sensorium a perception of those vibrations of air, which impart to more perfect animals the sense of sound, so they may also ". convey a perception of those undulations of the luminiferous ether, which (adopting the Huygenian undulatory theory of light, as revived and explained by Dr. T. Young), enable those animals which possess true eyes to enjoy the sense of vision!”

4 But this now seems, &c.] This sentence was substituted, in the 6th edition, for the following passage. "And for my own part, after much enquiry, I am not satisfied that these are eyes, or that those black and atramentous spots which seem to represent them are any ocular realities for if any object be presented unto them, they will sometimes seem to decline it, and sometimes run against it; if also these black extremities, or presumed eyes be clipped off, they will notwithstanding make use of their protrusions or horns, and poke out their way as before again, if they were eyes or instruments of vision, they would have their originals in the head, and from thence derive their motive and optic organs, but their roots and first extremities are seated low upon the sides of the back, as may be perceived in the whiter sort of snails when they retract them.'

That they have two eyes is the common opinion; but if they have two eyes, we may grant them to have no less than four, that is, two in the larger extensions above, and two in the shorter and lesser horns below; and this number may be allowed in these inferior and exsanguineous animals,5 since we may observe the articulate and latticed eyes in flies, and nine in some spiders: and in the great phalangium spider of America, we plainly number eight.

But in sanguineous animals, quadrupeds, bipeds, or man, no such number can be regularly verified, or multiplicity of eyes confirmed; and therefore what hath been under this

5 and this number may be allowed, &c.] This remark, in the 6th edition, supplies the place of the following:-the succeeding paragraph which also occurs in all the earlier editions, was omitted in the 6th"which will be monstrous and beyond the affirmation of any.

"Now the reason why we name these black strings eyes, is because we know not what to call them else, and understand not the proper use of that part, which indeed is very obscure, and not delivered by any, but may probably be said to assist the protrusion and retraction of their horns, which being a weak and hollow body, require some inward establishment to confirm the length of their advancement, which we observe they cannot extend without the concurrence hereof; for if with your finger you apprehend the top of the horn, and draw out this black and membranous emission, the horn will be excluded no more; but if you clip off the extremity, or only singe the top thereof with aqua fortis, or other corrosive water, leaving a considerable part behind, they will nevertheless exclude the horns, and therefore explorate their way as before; and indeed the exact sense of these extremities is very remarkable, for if you dip a pen in aqua fortis, oil of vitriol, or turpentine, and present it towards these points, they will at a reasonable distance decline the acrimony thereof, retiring or distorting them to avoid it ; and this they will nimbly perform, if objected to the extremes, but slowly or not at all if approached unto their roots."

The various readings given in this and the preceding note, prove that the earlier opinions of Sir Thomas were more in conformity with the sagacious assertion of the great naturalist of antiquity, and, I may add, with the conclusions which the investigation of Sir Everard Home, and other distinguished naturalists, have recently led them to form. The paper by Mr. Brayley, referred to in note 3, p. 318, will be found to contain a detailed and very interesting account of those investigations. Sir E. Home has pointed out the mistake of Swammerdam, whose microscopic examinations led him to consider the black rete mucosum, at the point of the horn, as nigrum pigmentum, and a pellucid part which he found there, as the cornea. Sir Thomas was probably misled by similar investigations, or he might have seen Swammerdam's work, which appeared in Dutch some years before the sixth edition of the Vulgar Errors.

}; d delivered, concerning the plurality, paucity, or anom ituation of eyes, is either monstrous, fabulous, or und thin never seen, includes good sense or meaning. And mwe receive the figment of Argus, who was an hierogly ck of heaven, in those centuries of eyes expressing th rs, and their alternate wakings, the vicissitude of day an night. Which strictly taken cannot be admitted, for th subject of sleep is not the eye, but the common sense, whie once asleep, all eyes must be at rest. And therefore what i delivered as an emblem of vigilancy, that the hare and lio do sleep with one eye open, doth not evince they are an more awake than if they were both closed. For the oper eye beholds in sleep no more than that which is closed, an no more one eye in them than two in other animals that slee with both open, as some by disease, and others naturally which have no eyelids at all.

As for Polyphemus, although the story be fabulous, the monstrosity is not impossible. For the act of vision may be performed with one eye, and in the deception and fallacy o sight, hath this advantage of two, that it beholds not objects double, or sees two things for one. For this doth happen when the axis of the visive cones, diffused from the object fall not upon the same plane, but that which is conveyed into one eye, is more depressed or elevated than that which enters the other. So if, beholding a candle, we protrude either upward or downward the pupil of one eye, the object will appear double; but if we shut the other eye, and behold it with one, it will then appear but single, and if we adduce the eye unto either corner, the object will not duplicate, for in that position the axis of the cones remains in the same plane, as is demonstrated in the optics and delivered by Galen, in his tenth, De usu partium.

Relations also there are of men that could make themselves invisible, which belongs not to this discourse, but may

6 it beholds not objects double.] In connection with this very curious question of single vision with two eyes, Dr. Wollaston read a short paper to the R. S. in February, 1824, on semi-decusation of the optic nerves. A subject to which he had been led by a singular species of blindness which had affected him-in which he had suffered a temporary loss of sight on the left side only of both eyes. See Quarterly Journal, vol. xvii. p. 227.

rve as notable expressions of wise and prudent men. " contrive their affairs, that although their actions be st, their designs are not discoverable. In this action ere is nothing left of doubt, and Giges ring rema th till amongst us, for vulgar eyes behold no more of wise han doth the sun; they may discover their exterior d utward ways, but their interior and inward pieces he only ees, that sees into their beings.

'n

CHAPTER XXI.

That the Chameleon lives only upon air.

CONCERNING the Chameleon,7 there generally passeth an opinion that it liveth only upon air, and is sustained by no other aliment. Thus much is in plain terms affirmed by Solinus, Pliny, and others, and by this periphrasis is the same described by Ovid. All which notwithstanding, upon enquiry I find the assertion mainly controvertible, and very much to fail in the three inducements of belief.

And first for its verity, although asserted by some, and traditionally delivered by others, yet is it very questionable.

7 Concerning the Chameleon, &c.] It is singular that Sir Thomas has not mentioned the vulgar opinion that this reptile undergoes frequent changes of colour according to that of the bodies near it. He has assigned some probable grounds for its being supposed to feed on air, viz. its powers of abstinence and its faculty of self-inflation. It lives on insects, which it catches by means of its long gluey tongue, and crushes between its jaws. It has been ascertained by careful experiment that the chameleon can live without eating for four months. It can inflate, not only its lungs but its whole body, including even the feet and tail. The frequent variations of colour observed in the chameleon are by no means determined by those of surrounding objects. They depend on the volition of the animal, or the state of its feelings, on its good or bad health, and are, besides, subordinate to climate, age, and sex. A. Ross so resolutely withstands the Doctor's arguments against the common opinion, as even to assert that flies are eaten by the chameleon, "rather out of wantonness or for physic." He adverts indeed to the fact, only as giving a reason for the animal being provided with digestive organs; but says that the slime on the tongue is not intended for catching the flies, but for destroying serpents, on whose approach the chameleon drops some of the slime on the head of the serpent, which presently dies. Ovid.] See Metam. 1. xv. fab. 4. 1. 411.