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The food swallowed and entering the stomach is called "su" (crop) in birds, "du" (stomach/abomasum) in beasts, and "wei" (stomach) in humans. In ancient anatomical drawings of the stomach, the upper opening was depicted at the top of the stomach and named *Benmen* (Cardia). The lower opening was depicted at the bottom and named *Youmen* (Pylorus). They spoke of two gates, upper and lower, in the stomach, unaware that the stomach actually has three gates. The stomach was drawn as vertically elongated, unaware that it is horizontally elongated; not only is it horizontal, but it lies flat within the abdominal cavity. The upper opening, Benmen, faces the spine, while the base of the stomach faces the abdomen. The lower opening, Youmen, is also located on the upper part of the stomach,偏 towards the right hypochondrium and facing the spine. Approximately one cun to the left of Youmen, there is another gate named *Jinmen* (Fluid Gate). Above Jinmen is a tube named *Jinguan* (Fluid Tube), which is the pathway for fluid essence and water to exit the stomach.

Below the *Zongti* (General Connector, referring to the connective tissue linking organs), anteriorly it connects with the *Qifu* (Qi Mansion) and joins the small intestine; posteriorly it connects with the large intestine. Located above the stomach, it posteriorly connects with the liver, and the liver connects to the spine. This constitutes the physical structure below the diaphragm, where the Zongti links the solid tissues of the stomach, liver, and intestines. When food and drink enter the stomach, the food remains in the stomach, while the fluid essence and water first flow out through Jinmen into Jinguan. Jinguan is about one cun long and divides externally into three branches. The clear portion of the fluid essence enters the *Sui Fu* (Marrow Mansion) to transform into marrow. The turbid portion of the fluid essence, via the upper branch, enters the *Xue Fu* (Blood Mansion) when lying down, transforming into blood along with the blood. The water portion passes through the middle of the liver via the lower branch and enters the spleen. Within the center of the spleen is a tube with a delicate, intricate structure, named *Longguan* (Exquisite Tube). The water flows from Longguan, dividing to both sides, and enters the *Chushuidao* (Water Outlet Channel). Chushuidao resembles a fish net, commonly known as "Wangyou" (Net Oil). Water渗ates through Chushuidao, infiltrates into the bladder, and transforms into urine. Examining this section of water discharge from Chushuidao is the most difficult. Since observing human viscera in the second year of the Jiaqing era, I have seen Chushuidao appearing like a bell full of water or empty of water, yet the principle remained unclear. Later, in diagnosing patients, I examined individuals who died of chronic illness; some drank heavily before death, some little, and some not at all, yet water remained in the abdomen afterward. Comparing this with previous observations, although this aligns closely with the theory of water discharge from Chushuidao, I dared not accept it as an absolute certainty. Subsequently, by comparing with livestock, animals slaughtered immediately after feeding had nets filled with watery bells, whereas animals not fed for three to four days had no such empty bells upon slaughter. Thus, the water discharge from Chushuidao was confirmed.

As stated previously, food enters the stomach and stays there, while fluid essence and water flow out from Jinmen. Although the aperture of Jinmen is only as wide as a chopstick, if it can expel fluid essence and water, why could it not expel thin porridge? Although the aperture is chopstick-wide, the gastric tissue at this site is very thick, and the surrounding walls compress to narrow the passage, allowing water to exit but preventing solid food from passing. Furthermore, inside the stomach, one fen to the left of Jinmen, there is a lump shaped like a date pit, named *Zheshi* (Food Blocker), which serves to block food while allowing water to pass. Only after the fluid essence and water have flowed out does the food begin to rot and ripen, gradually entering the small intestine to transform into feces. Why does the small intestine transform food into feces? Because outside the small intestine is the Qifu; the Qi of Qifu envelops the small intestine. Between the exterior of the small intestine and the interior of Qifu lies the reservoir of Yuan Qi (Original Qi), which digests the food. Refer to the earlier mention of Qifu here. The transformed feces enter the large intestine and are expelled from the anus. This chapter records the complete process: fluid essence exits the stomach via Jinmen to generate essence and blood; water flows via Longguan and Chushuidao into the bladder to become urine; and food enters the small intestine from the stomach, where Original Qi steams and transforms it into feces.