Whether blood is the nutriment for the stomach.
One inquires further whether blood is the nutriment for the stomach.
It seems not. For each member is nourished by that which it digests. But the stomach does not digest nutriment in the blood but in the chyle. Therefore, it is not nourished by blood but by chyle.
Moreover, the first generation of blood is in the liver. But nutriment does not pass from the liver to the stomach, but vice versa. Therefore, etc.
To the contrary. "Blood is the last food of all the members," according to the Philosopher, and therefore also of the stomach, since it is a member.
Moreover, the veins are vessels for the blood. But there are veins in the stomach. Therefore, etc.
One must reply that there are two webs or tunics in the stomach, namely, an exterior and an interior one. The exterior is nourished by blood, but the interior is nourished by chyle. But because the Philosopher says that "blood is the last food of all the members," one can say that the stomach is nourished by blood with respect to each web or tunic. For even though blood is not generated in the stomach, nevertheless after the generation of the blood in the heart is completed, it is diffused through fine veins to all the members. Thus, sometimes the stomach is even warmed when it separates the chyle from the blood, since it is strengthened and grows warm and becomes stronger. Nevertheless, its perfected nutrition is received from blood; otherwise, its web would not be covered with thin veins.
One can respond to the arguments in this way, because each arrives partially at the truth. And this is why, etc.
Whether several intestines are required beyond the stomach.
One inquires further whether several intestines are required beyond the stomach.
And it seems not. Because what nature can perform through one, it does not perform through several. But the pure is separated from the impure in the stomach. Therefore, the impure can adequately be expelled from the stomach without an intestine.
Moreover, if intestines are required beyond the stomach, then either they are required for further digestion or only for expulsion. If only for expulsion, then one would suffice. If for digestion, then they would be wider above and narrower below. But the opposite is apparent in ruminant animals and in others, like the human and the dog.
The Philosopher says the opposite.
One must reply that intestines are necessary for the sake of the belly, since the stomach is not joined immediately to the anus, because then it would be excessively cooled and cold impedes digestion. And this is why it is separated from the anus by some medium, and that medium is the intestine. But although the first digestion occurs in the stomach, nevertheless digestion is not completed there, because, just as that which is pure and separated by the stomach is not absolutely pure but rather is further purified and digested in the members, so too the impurity expelled by the stomach is not absolutely impure. Rather, something pure can still be separated from it, and this is why there are several intestines beyond the stomach, in order to digest it further. But because digestion is of two typesof the pure and of the impurefor this reason some intestines serve to digest what exits from the stomach, when it is pure, and others serve to digest it when it is impure. But because there are three [stages] in digestion, namely, a beginning, a middle, and an end, for this reason three intestines serve each digestion, so that what is begun in the first is assisted in the second and completed in the third. And this is why in individual animals, for the most part, there are six intestines. Nevertheless, these are ordered differently in different animals, since in those that live on crude nutrimentlike sheep, and oxen, and the likethe upper intestines are narrower and the lower ones are wider, because the more their nutriment is digested the cruder is that which remains behind. And because at the end it is especially crude, this is why the lower intestines are wider. But because at the beginning it is thinner and liquid, this is why the upper intestines are narrower. But it is just the opposite in the human and the dog, for a contrary reason, since the human and the dog are alike in many ways. They have a big appetite, and this is why they have a small stomach. If they had a large stomach, many would confound themselves with a desire beyond all bounds, because the diaphragm and, as a result, the spiritual members would be injured by the repletion of the stomach. A human and a dog live on almost the same nutriment, namely, what is thin and easily convertible, and this is why nature arranged for them narrower lower intestines, so that the nutriment would not exit too quickly. And an indication of this is that a dog does not defecate without pain.
Through this a solution to the arguments is apparent.