Urine and Bile

Book 1 showed that Erasistratus and all those who wrote about urinary secretion must acknowledge that the kidneys have some faculty which attracts to them this particular quality existing in the urine.167

But urine is carried through the kidneys into the bladder by 2 methods:

1. The blood into parts of the animal by another
2. The yellow bile separated out

For when once there has been demonstrated in any one organ, the drawing, or so-called epispastic168 faculty, there is then no difficulty in transferring it to the rest.

Nature did not give a power such as this to the kidneys without giving it also to the vessels which abstract the biliary fluid,169 nor did she give it to the latter without also giving it to each of the other parts.

Assuredly, if this is true, we must marvel that Erasistratus should make statements concerning the delivery of nutriment from the food-canal170 which are so false as to be detected even by Asclepiades.

Erasistratus asserts that if anything flows from the veins, one of two things must happen:

1. A completely empty space will result or
2. The contiguous quantum of fluid will run in and take the place of that which has been evacuated.

Asclepiades, however, has 3 effects:

1. There will be an entirely empty space, or
2. The contiguous portion will flow in, or
3. The vessel will contract.

This is because when reeds and tubes aresubmerged in water, and are emptied of the air then either a completely empty space will be left, or the contiguous portion will move onwards;

In the case of veins this no longer holds, since their coats can collapse and so fall in upon the interior cavity. It may be seen, then, how false this hypothesis—by Zeus, I cannot call it a demonstration!—of Erasistratus is.

Erasistratus supposed that:

• the stomach can compress the veins
• the veins can contract the contents of the stomach and propel them forwards.172

No plethora173 would ever take place in the body, if delivery of nutriment resulted merely from the tendency of a vacuum to become refilled.

The principle of the refilling of a vacuum is a necessary addition if:

• the compression of the stomach becomes weaker the further it goes, and cannot reach to an indefinite distance
• some other mechanism makes the blood go in all directions

there will not, however, be a plethora in any of the parts coming after the liver,175 or, if there be, it will be in the region of the heart and lungs;

for the heart alone of the parts which come after the liver draws the nutriment into its right ventricle, thereafter sending it through the arterioid vein176 to the lungs (for Erasistratus himself will have it that, owing to the membranous excrescences,177 no other parts save the lungs receive nourishment from the heart).

If, however, in order to explain how plethora comes about, we suppose the force of compression by the stomach to persist indefinitely, we have no further need of the principle of the refilling of a vacuum, especially if we assume contraction of the veins in addition—as is, again, agreeable to Erasistratus himself.

Chapter 2

I will refute those who object to the principle of attraction.

Nobody has explained any other cause or means for the secretion of urine.

We would appear mad if we said that:

• the urine passes into the kidneys as a vapour.
• a vacuum is refilled;178
• This idea is foolish in the case of blood
• It is impossible and nonsensical in the case of the urine.179

This is one blunder made by those who dissociate themselves from the principle of attraction.

Another is that which they make about the secretion of yellow bile. For in this case, too, it is not a fact that when the blood runs past the mouths [stomata] of the bile-ducts there will be a thorough separation out [secretion] of biliary waste-matter. “Well,” say they, “let us suppose that it is not secreted but carried with the blood all over the body.”

But, you sapient folk, Erasistratus himself supposed that Nature took thought for the animals’ future, and was workmanlike in her method; and at the same time he maintained that the biliary fluid was useless in every way for the animals. Now these two things are incompatible. For how could Nature be still looked on as exercising forethought for the animal when she allowed a noxious humour such as this to be carried off and distributed with the blood?…

This, however, is a small matter. I shall again point out here the greatest and most obvious error. For if the yellow bile adjusts itself to the narrower vessels and stomata, and the blood to the wider ones, for no other reason than that blood is thicker and bile thinner, and that the stomata of the veins are wider and those of the bile-ducts narrower,180 then it is clear that this watery and serous superfluity,181 too, will run out into the bile-ducts quicker than does the bile, exactly in proportion as it is thinner than the bile!

How is it, then, that it does not run out? “Because,” it may be said, “urine is thicker than bile!” This was what one of our Erasistrateans ventured to say, herein clearly disregarding the evidence of his senses, although he had trusted these in the case of the bile and blood.

For, if it be that we are to look on bile as thinner than blood because it runs more, then, since the serous residue181 passes through fine linen or lint or a sieve more easily even than does bile, by these tokens bile must also be thicker than the watery fluid. For here, again, there is no argument which will demonstrate that bile is thinner than the serous superfluities.

But when a man shamelessly goes on using circumlocutions, and never acknowledges when he has had a fall, he is like the amateur wrestlers, who, when they have been overthrown by the experts and are lying on their backs on the ground, so far from recognizing their fall, actually seize their victorious adversaries by the necks and prevent them from getting away, thus supposing themselves to be the winners!