kidneys, peradventure because they are moister then ordinary, and contain a more thin melancholy Juyce, which because they do not strongly enough expel, but treasure it up rather, therefore these Cases are widened. But in grown persons they are straitned, and become less, though they abound more with Melancholy, part∣ly because the Melancholy being gathered by degrees, is through the strength of nature by degrees expelled; partly, because the Serum in hotter persons is dried up, wherewith the new born Infant abounded; and partly because as the Reins grow bigger, they are compres∣sed. Yet I have once observed them in a grown per∣son, by reason of aboundance of black Choler, twice as big as ordinary, whereas commonly they are no big∣ger then a large vomiting Nut.
They have an apparent internal Ca∣vity, both in persons grown and new∣born babes, compassing the inner cir∣cumference of the whole Case as it were, in which they are found to contain a dreggie and black humor, so that even the inner sides are coloured with the said black∣ness. In Infants I have seen to my thinking wheyish blood in them. I admire that Riolanus could not, or would not see this Cavity, for though he cries that it is so small, that it will hardly admit a little Pea, yet is it somtimes wider, and alwaies so large, as to contain many peasen compressed, and we can thrust a Probe into it, this way and that way, without violence. It contains therefore a large Cavity, respecting the smal∣ness of its Body. Nor hath Nature ever labour'd in vain, no not in the smallest spaces of the Capillary Veins. It is a small matter which they can hold, yet it may be counted much, because it is successively re∣ceived in, and cast out again. This Humor might have been indeed allayed and sweetned by the admix∣ture of blood, as Choler also might, yet Vessels and Receptacles are ordained for both these Excrements, that the blood might not be polluted.
In Shape and Substance they many times resemble the kidneys, save that their substance is a little looser; so that they seem little kidneys resting upon the great ones. Which perhaps was the Reason that Casserius did call them Auxiliary kidneys: But more frequently their substance is flat like a Cake (howbeit hollow within) and their shape is round-long and somwhat square. Somtimes they are three corner'd, seldom round; for they are seldom seen in one and the same shape.
They are knit where they rest unto the external Membrane of the kid∣neys so fast, that negligent Disse∣cters, when they take out the kidneys, leave them stick∣ing to the Membrane of the Diaphragma or Midriff. And this is the Reason that many observe them not.
They have Vessels: Veins, and Arteries, derived to them from the middle of the Emulgents. Somtimes also a Vein is sent thither from the kidney, and somtimes also a branch near the Liver from the Cava is brought there∣to, somtimes also from the Vena adiposa, and somtimes from all those places, somtimes with a single, other∣whiles with a double branch. Somtimes they have a single Artery from the Emulgents, somtimes a double one; and otherwhiles they have from the Trunk of the Aorta, one while a single branch, otherwhiles three together.
These Cases have Nerves also. For about the begin∣nings of the Arteries of the Mesentery, some branches of Nerves mixed together are produced, one part of which goes unto the kidneys, and these Cases which rest upon them.
Their use hath been hitherto unknown. If it may be allowed to conjecture, as doubtless it is, due consideration being had to the Structure and Passages; we may say, that a thick and excrementiti∣ous black-cholerick humor, is detained in these Cases, which had not been purged from the Blood made in the Liver, or Spleen, or both, but especially that blood which we formerly proved to be made in the Spleen; which is here kept and digested, because it could not pass through the narrow waies of the kidneys. Nor let the ascending of an heavy substance trouble us, which ever and anon happens in the Body, by means of the expulsive and attractive Faculty of some Part; yea and vehement attraction is advantaged by the highness of Situation in motions Spiritual. Hence also perad∣venture it is that Urins are somtimes black, when at a∣ny time this Humor is collected in the Cases, in too great a quantity. Where also may be often doubtless, the seat of some morbifick cause, especially of Melan∣choly. And the reason why melancholick persons are thereby little pained, is because the smallness of the Nerves, and the thickness of the Hu∣mor, do render the Sense dull. The re∣nowned Veslingus agrees with me in this use, but he shews not whence, nor how the humor comes. For he conceives they help to draw the wheyish humor, and that they treasure up a parcel of black Choler, which furthers the separation of Whey from the Blood, like Runner. Olhafius will have them to receive the thick and terrestrial Excrements of the kidneys, which remain after their Dige∣stion. And therefore because a greater Bowel hath more Excrements then a lesser, the Conceptacle for the right kidney was to be larger, and that for the left lesser, and therefore the right side Case is greater then the left side, because the right kidney is greater then the left. But no man hath thought of the waies by which the black blood should be discharged into these Cap∣sulae or Cases. The Arteries do easily occur to such as hold the Circulation of the blood. For according to the old Opinion, a way is readily found to these Cap∣sulae from the Emulgent, or from the Trunk of the A∣ota it self, which bringing Nutriment such as it is, do withal unlade the Excrement of the Arterial blood, which was not evacuated formerly. But how it returns out of the Capsulae, how it comes to the kidneys to colour the u∣rins black, is not so easie to shew, for the Veins end in the Emulgents, or in the Cava it self, seldom in the kidneys, and so either they should perpetually keep that excrementitious Juyce, which is unlikely, or send it back again to the Cava and the Heart, or they ought, verily, to enter the kidneys directly by the E∣mulgent Veins, without any hindrance by the contra∣ry motion of the blood going out of the kidneys. This contrary motion a thicker and stronger humor can ea∣sily overcome, manifold branches also opposing the same, as in Rivers we now and then see waters run contrary to the stream, by the banks and in the middle, by reason of some fountains opened. But oftentimes the Vein of the right side Case, is immediately inserted out of the Trunk ••f the Cava. And in such a chance, truly, either Capsula or Case is not sufficiently purged, whence arises some hidden Disease; or the cir∣cular motion •…•…e there neglected, which in the