13. Of Snails and Leeches, and whether all Animals have blood.
WHether Snails have a row of small teeth, orderly placed in the Gums, and divided into several smaller and greater; or whether they have but one small bended hard bone, which serves them instead of teeth, to bite out pretty large and half-round bits of the leaves of trees to feed on, Experimental Philoso∣phers may enquire by the help of their Microscopes; My opinion is, That Snails are like Leeches, which will not onely bite, but suck; but this I do verily be∣lieve, that Snails onely bite Vegetables, not Animals, as Leeches do; and though Leeches bite into the skin, yet they do not take any part away, but suck onely out the juicy part, that is, the blood, and leave the grosser substance of flesh behind; and so do Snails bite into herbs, to suck out the juicy substance, or else there would be found flesh in Leeches, and herbs in Snails, which is not; so that Snails and Leeches bite for no end, but onely to make a passage to suck out the juicy parts; and therefore I cannot perceive that they have bones, but I conceive their teeth or parts they pierce withal, to be somewhat of the nature of stings, which are no more Bones then the points of Fire are; I do not certainly af∣firm they are stings, but my meaning is, that they are pointed or piercing figures, that is, as I said, of the nature Page 34 of stings, there being many several sorts of pointed and piercing figures, which yet are not stings, like as there are several sorts of grinding and biting figures which are not teeth; for there are so many several sorts of fi∣gures in Vegetables, Minerals, Animals and Ele∣ments, as no particular Creature is able to conceive. Again, it is questioned, whether those Creatures that suck blood from others, have blood themselves, as naturally belonging to their own substance; and my o∣pinion is, that it is no necessary consequence, that that should be a part of their substance on which they feed; food may be converted into the substance of their bo∣dies by the figurative transforming motions, but it is not part of their substance before it is converted; and so many Creatures may feed on blood, but yet have none of themselves as a natural constitutive part of their be∣ing: besides, there are Maggots, Worms, and seve∣ral sorts of Flies, and other Creatures, that feed upon fruits and herbs, as also Lobsters, Crabs, &c. which neither suck blood, nor have blood, and therefore blood is not requisite to the life of every animal, al∣though it is to the life of man, and several other animal Creatures; Neither do I believe, that all the juice in the veins, is blood (as some do conceive) for some of the juice may be in the way of being blood, and some may have altered its nature from being blood, to cor∣ruption, which later will never be blood again, and some may onely be metamorphosed from blood, and Page 35 reassume its own colour again; for it is as natural for blood to be red, as for the Sun to be light: Where∣fore when some learned are of opinion, that those white, or yellow, or black juices which are found in the veins of small insects, are their blood, they might as well say, that brains are blood, or that the marrow in the bones, is blood; or if the brain should all be turned to water, say, that this water is brains; which would be as much as if one should call a mans body turned to dust and ashes, an animal Creature, or a man; for there are na∣tural properties which belong to every Creature, and to each particular part of a Creature, and so is blood in some animals a natural vital part proper to the con∣servation of its life, without which it cannot subsist: for example, a young Maid in the Green-sickness, when her veins are fuller of water, then blood, appears pale, and is always sickly, weak and faint, not able to stir, by reason her veins are fuller of water then blood, but were it all water, she would presently die. Where∣fore all juices are not blood; nay, I cannot believe as yet, that those they call veins in some insects, are veins, much less that they contain blood, and have a circula∣tion of blood, nor that their motions proceed from Muscles, Nerves and Tendons; but this I may say, that the veins are the proper and convenient vehicles or receptacles of blood, as the head is of brains, and the bones of marrow; also it is as proper for blood to be red, as for veins to contain blood, for bones to contain Page 36 marrow, and for the head to contain brains; and when they alter or change from their particular na∣tures, they are no more blood, brains nor marrow: Wherefore those Creatures that have a juice which is not red, have no blood; and if no blood, they have no veins. I will not say, that all those that have veins must of necessity have them full of blood; for in Dropsies, as also in the Green-sickness, as I men∣tioned above, they are fuller of water then blood, but they must of necessity have some blood in their veins, by reason the veins are the most proper recep∣tacles for blood, and no man can live without blood, but when all blood is turned to water, he must of ne∣cessity die.