A Letter from Mr. William Musgrave Fellow of New College Oxon: and One of the Secretaries of the Royal Society, to the Learned Dr. Martin Lister, wherein He Endeavors to Prove That the Lacteals Frequently Convey Liquors That are Not White

A Letter from Mr. William Musgrave Fellow of New College Oxon: and one of the Secretaries of the Royal Society, to the Learned Dr. Martin Litter, wherein He endeavors to prove that the Lacteals frequently convey Liquors that are not White. Honored Sir, THAT considerable Experiment of Yours, made for altering the colour of the Chyle in the Lacteal Veins, (which I have found to succeed, by injecting a pint of a Decoction of Stone-blew, into one of the Intestina tenuia of a Dog, kept fasting 36 hours &c.) does not only claim my assent to the Conclusion you draw from it, viz. That a color'd Liquor may find admittance into the Lacteal Vessels; but also has (in part) been the occasion of my inclining to an Opinion, That the Lacteals frequently convey liquors which are not White: In Confirmation of which Proposition, I must beg leave First to give you an account of some Experiments I have lately made, relating to this matter; and secondly to offer at some Deductions from them: The Experiments are of three kinds; 1. I kept 2 Dogs fasting, one 48 hours, the other 3 daies, and then open'd them; in both a considerable number (above 20, where fowest) of the Lacteals appeared Pelucid, like Lymphatics; only not so full and turgid, as those under the iver are generally, or as the Lacteals themselves are sometimes, seen: I cut several of them in each Dissection, and immediately a Transparent liquor flowed out of the Orifice. 2. A Dog, which had neither eaten, nor drank, in three daies, was suffered to lapp a quart of common water; an hour after which, he was opened; the Lacteals shewed themselves in a great number (perhaps above 60,) all impid, from the liquor contain'd in them, as in the former Experiments: part of the water was suppos'd to be fixt in the Stomach and small Guts; for the quantity of water seen there, was far greater, than that in the prime via of either of the Dogs kill'd fasting. This Experiment was repeated with very little alteration in the trial, and the same success as before. 3. Another Dog, after three daies fasting, had a piece of fat Meat given him; an hour and half after which, he lapt (about) a Quart of common Water, and half an hour after this, was open'd: I first tied the Ductus Thoracicus; then examin'd the Lacteals; which I saw in as plentiful a number, and as full as (perhaps) they were ever seen in this Species of Animals: eight, or ten, of them at the first opening of the Dog, appear'd perfectly white; very many of a faint diluted white; but most of them were Pellucid; especially at the latter end of the Dissection; by which time, several, which at first were either of a lively, or of a fading White, were now grown transparent: that I might satisfy myself as to this difference in the colour of these vessels, I open'd the Intestinum Jejunum, and Ileon, in several places; and found the water was got as far as the Cæcum; and had carried down diverse little parcels of the meat with it; by which means the liquor seen in the Lacteals, at the first view of them, was either of a perfect, or of a diluted white, or else pellucid, according to the mixture of the meat with the water in the guts. I ordered about 3 pints of broth to be given a Dog, which had been kept fasting 24 hours, and opening him 4 hours after this, I observed the lacteals, beginning at the Duodenum, (with which the other small guts, and stomach) was very much distended with the matter of the last meat: all the lacteals, that I saw at first, were of a perfect white colour; several of which I pressed between my fingers, drawing them from the circumference toward the Center of the Mesentery, by which means I found, that the Chyle, contained in these Vessels, appeared White, when it ran in a shallow stream, as well as when it filled the lacteals: Viewing the rest of these Vessels along toward the Caecum, I observ'd, that, near the middle of the Intestinum Ileon, they began to be of a more diluted white, and a little farther, they were really pellucid, and as turgid, to appearance as those that were White; after which turning back again toward the stomach, I saw the same Vessels (I think) in as great numbers as at first (perhaps above 80) but the colour of most of them was chang'd, for they were all now pellucid: some 3, or 4 which I at first cut asunder for my better enquiry into the white Chyle contain'd in them at that time, being limpid together with the rest. The same thing succeeded in a Dog kept fasting 2 days, and then opened 3 hours after he had lapt 3 pints of Milk, part of which was seen in the stomach of the Dog: about 15 of the lacteals, arising from the Duodenum, were white; above 100, proceeding from the Intestinum Jejunum, and Ileon, were, more, or less, transparent; as also were those of the Duodenum at the latter end of the operation. 2. This being the Relation of matter of Fact, let us now, now, in the second place, examine, what is the Con- sequence, what the Effects, of all this slaughter. 1. The Experiments of the first kind do sufficiently prove, that the Lacteals convey not only Chyle (which results from aliments lately taken into the Stomach, and may be call'd Liquor Novitius,) but also another humor separated (as is most probable) from the blood, and now returning to it again; which (by means of the aforesaid Experiments,) may be seen purely by it self, without any mixture of Chyle with it. As to the place, where this liquor Refluss (for so we will hereafter term it) parts from the blood; particularly whether it be a Lympha, properly so call'd, arising in the musculose Veines of the Intestines? Or whether it be a liquor emptied into the hollow of the Stomach, and Intestines, from the Pancreas, Glandularum plexus Fra- giformes, and perhaps the Liver; or thirdly whether it proceeds partly the former, partly the latter, way; is a Question not easily determin'd. Caspar Bartholin, who looks on himself (and it may be justly enough) as the first observer of the Lacteals appearing sometimes limpid, like Lymphatics, has these words in favor of the former of those Opinions; having spoken before of the glandulose Tunics of the Intestines. He saies [si verum sit, quod magnam veri speciem habet, Lymphatica ab aliis partibus non glandulosis oriri, has (sicilicet lacteas) ab In- testinis Lympham superfluam revchere dicam.] Diaphrag- matis structura pag. 95. But as far as I can judge at present, it seems not unreasonable to derive at least part of this Liquor from the hollow of the Intestines; if we consider, that the Pancreas, and Glandularum Plexus Fragiformes, (not to mention the Liver) do daily dis- charge a liquor into the Intestines; which (consider- ing that Dogs, after three daies fasting, will, as I have often observ'd, have very hard faces in their Intestina Recta.) Recta) we cannot well dispose of any other way, then by saying, it reenters the blood by the Lacteals, and is that very liquor, which conduces to the making some of them appear transparent after so long a fast. 2 It seems probable, from the same forementioned Experiments of the first kind, That the Lacteals are very seldom, or never, all empty at the same time; for tho the Chyle flows only in certain Tides, or Flashes, pro ratione Ingestorum; yet the Liquor Refluus, running in a more constant stream, does, when there is no Flash of Chyle going in, keep the Lacteals from being absolutely empty. 3. But, to come nearer to my purpose, tis farther evident from the same Experiments, that this Liquor Refluus is, in its own nature, transparent; and passes such thro the Lacteals, after long fasting, when no Chyle is mixt with it; which is no inconsiderable step to the making out of my Proposition, if we recount how long, and how often, very many Quadrupeds, beside Men, do fast from all sorts of aliment; during which time, after the Chyle of the last Meat, or time of drinking, is all mixt with the blood, we may suppose that this pellucid Liquor Refluus, goes alone into the Lacteals. 4. The Experiments both of the second, and third kinds, seem to intimate, that a great part of the Chyle itself is, in its journey thro the Lacteals, altogether Limpid: against which if it be objected, that some of the Lacteals were, in a like manner, pellucid, in all the Experiments, of all the three kinds, and therefore it does not appear but that they may be filled with a liquor Refluus in the last cases, as well as for certain) they were in the first Case; to this Objection, beside what may be answered from the extraordinary number, and fulness of the limpid lacteals in the last kinds of Experiments, comparing these Vessels with those of the same same sort seen in the first kind (which comparative excels cannot be imputed to any cause so reasonably, as to the matter given the Dogs a little before the Dissections of the last kinds;) beside this I say, it may farther be replied, that in all the Instances of the 2d and 3d Cases, a considerable quantity of aliment was taken in by each Dog, not long before his Death; That some of this matter was seen in the primæ via of every one of them when dead; (an argument it was not all Distributed;) That there is no way, certainly known, by which liquors are discharged the primæ via, in this Species of Animals, beside Vomiting, Seige, and by the Lacteals; and that, seeing neither of the former took place, it may not be unreasonable to suppose, That part of this matter was, at each dissection, in its way thro' the Lacteals to the blood; all the operations being at such distances from the time of the matter's being taken in, at which most liquid aliments are observed to well up the Lacteals. But farther, whoever shall insist upon this Argument, if he derives his liquor Refluus from the Musculofc Tunics of the Intestines, is liable to the objection before mentioned against that opinion; if from the Pancreas, Glan-dularum Plexus Fragiformes, and Liver, will find it no easy thing to account, why this liquor should be admitted the Lacteals, and the water (taken in specie in the Experiments of the 2d kind; as also in the first Instance of the 3d kind; and included in the broth given in the second instance of the third kind) should be excluded; altho' in some of these Instances it was seen to have almost reacht the Cæcum: especially since it is sufficiently prov'd, That Decoctions of Indigo and Stoneblow (of which Decoctions far the greatest part is Water) have found the way into the Lacteals. Now if it be not too precarious to suppose, That the Liquor, seen in the Pellucid Lacteals of the last kinds of Experiments, did, in a great measure (for I by no means exclude the liquor Refluus) consist of the matter lately taken in before the Dogs were opened; we may with good reason imagine, That water, drunk on an empty Stomach, (as it was in the second Case) by several other Quadrupeds, and Men, as well as Dogs, will pass the Lacteals, not under a white colour, but rather Pellucid; and these Cases are not uncommon amongst us; particularly this seems to hold true in those, who drink great quantities of Diuretic Mineral Waters, in the morning, fasting; of which suppose any person takes and evacuates, 3 Quarts, by Urine, in the forenoon; and, with his dinner, and in the afternoon, drinks 3 Pints of Bear, or the like (allowing that all the Chyle produced from what he takes in at dinner, and in the afternoon, amounts to 2 Quarts, and that these 2 Quarts of Chyle are perfectly White; which in all probability is not true; yet, I say, according to this favourable account) three Pints of Pellucid, for 2 of white Chyle, will pass the Lacteals in this person, in 24 hours. And what is here said of Water, is not unlikely to be true (mutatis mutandis) of several other liquors, as Wine, Bear, &c. at least so far as that they may not pass white thro the Lacteals, which is sufficient for my purpose. Again, if this principle be true, the third kind of these Experiments will go yet farther and argue, That the whole quantity of Chyle, arising from some sorts of Meat, and Drink, taken either at, or near, the same time; or from some sorts of Meat taken alone; is not always white; for the Lacteals, which appear'd perfectly white in the several Instances of the third kind, were far inferior in number to those that were Pellucid in the same Dissections: But the proportion of the White, to the Diluted, and the Pellucid, Chyle, depends upon so very many Circumstances, (as the quality of both meats, and drinks; the distance between the time of their being taken; and the propor- tion of one to the other) that it seems almost impossible to determine it. From the Premises it appears, there is some reason to induce us to think, that the Lacteals frequently convey Liquors, which are not white; and that Chyle may (not improperly) be divided into three sorts at least, viz. White, Pellucid, and Intermediate to these; contrary to the opinion of those Anatomists, who thought it to be always white, as that word is contradistinguished to [Pellucid]; although [Chyle]. They understood (as I likewise do) the Effect of Drink, as well as Meat, Concocted. This (Sir!) is the sum of what I shall trouble you with at present, concerning this subject; an account of which I here send you, having been assur'd, it will meet with a welcome at your hands; and indeed the whole being a Building on your foundation, the right and Title of it does of Consequence belong to You: But that which gives the greatest encouragement to the writing of this Letter, is, that I know I write to one, who has Candor to excuse, as well as Judgment to discover, my Errors; to the former of which I must of necessity be oblig'd, and am not averse to the latter; but shall rather be glad, if I may know your sentiments concerning the matter in hand, which way soever they shall tend; whether to a Confirmation, or a Confutation of this Opinion.