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Leech (Shuizhi, *Hirudo nipponica*)

Taste: Salty, bitter. Nature: Neutral, slightly cold. Toxicity: Toxic.
Actions: Primarily expels evil blood (bad blood), stasis blood, amenorrhea, breaks blood masses (hematoma/masses), accumulations, treats infertility, promotes urination, and induces abortion.
Alternative Names: Qi (qí), Zhizhang.
Source: Grows in the ponds and marshes of Leize.
Harvesting: Collected in May and June, dried in the sun.

Tao Hongjing stated: "Qi" (pronounced like "qi"), there are now several types; here, the horse leech is used. Those that bite humans and have blood in their bellies are best when dried. Those from mountains and various small ones are not used. When King of Chu ate pickled sour vegetables, he swallowed one, which indeed removed the accumulated knots. Although it is considered a yin toxin, this is also due to the nature of the substance itself. The *Tang Bencao* annotation states: This creature includes grass leeches and water leeches. The large ones, up to a chi in length, are called horse leeches or horse qi. They can suck the blood of cattle, horses, and humans. Currently, people mostly use the smaller ones found in water, which are very effective; it is not necessary to use those with bellies full of human blood. As for grass leeches, they grow on grass in deep mountains. When people walk by, they attach to the calves and thighs without being noticed, then reproduce within the flesh, causing great harm. Mountain dwellers have their own treatments for them.

Chen Yuxi et al., according to the *Shu Ben*, state: After harvesting, keep them in a bamboo tube until dry, then soak in rice wash water overnight before drying again. Then fry them in winter lard until scorched yellow before use. Do not mistakenly collect stone leeches or mud leeches. Stone and mud leeches have pointed heads and thick waists, are red in color, and are not suitable for medicinal use. If ingested by mistake, they cause a sensation of smoke in the eyes, gradually leading to withering and damage. Now, only the smaller water leeches are used.

Chen Cangqi stated: Besides its original functions, for patients suffering from erysipelas (red and white wandering rashes) and carbuncles/swellings, take over ten leeches and let them feed on the affected area until the skin wrinkles and the flesh turns white; all will heal. In winter when leeches are scarce, dig them out from the ground, raise them in warm water to make them active, first wash away the saltiness from human skin, place them in a bamboo tube to suck blood. Within moments, they will detach after filling with blood; use hungry leeches subsequently. Cui Zhiti ordered pre-raising in the two capitals to prevent emergencies. When collecting dried leeches, stretch their bodies to make them long; remove those with eggs in the belly. This creature is hard to kill; even if roasted over fire, it resembles fish roe; smoked for three years, it remains alive when wetted. This explains King Chu's illness.

*Yaoxing Lun* states: Shuizhi acts as an envoy. It primarily breaks menstrual obstruction in women, preventing the formation of blood consumption nodules. It treats blood accumulations. Rihua Zi states: It fears calcined alum. It breaks nodular masses. However, it is extremely difficult to process; it must be finely chopped, then stir-fried over low heat until yellow to be ripe. Otherwise, it may produce offspring in the abdomen, causing harm.

*Tujing* states: Shuizhi grows in the ponds and marshes of Leize; nowadays, it is abundant in nearby rivers and pools. Also known as Qi. There are several types: those living in water are called Shuizhi or Mahuang; those in mountains are called Shizhi; those in grass are called Caoshi; those in mud are called Nishi. All attach to the thighs and calves of humans, cattle, and horses, biting and sucking blood. Severe cases enter the flesh, reproducing and causing great harm. Water leeches can be up to a chi long; use smaller ones for better efficacy. Collect in June, dry in the sun. One method says to collect them in a bamboo tube, wait for drying, soak in rice wash water overnight, then take out and dry. Fry in winter lard until yellow before use. Dried leeches should be stretched out; remove those with eggs. Ancient methods used live leeches to feed on sores, but these are hard to obtain in emergencies. Cui Zhiti ordered pre-raising for backup. This creature is extremely hard to kill; roasted over fire for a year, it can still survive when wet. Stone leeches etc. have pointed heads and thick abdomens, unsuitable for medicine. Mistaken use causes persistent smoke-like sensations in the eyes, gradually leading to withering and damage; this must be distinguished carefully.

Empirical Formula for treating fractures: Dry Shuizhi on a new tile, grind into fine powder, mix with hot wine and take 1 qian. If pain persists after a meal, take another dose until pain stops; then apply fracture-healing medicine, fix with splints, and wait for effectiveness.

Chu Yushi treated internal injuries from falls from heights or blows with divine efficacy. Mix 1 liang of Moschus (Shexiang) and 1 liang of Shuizhi, chop finely, stir-fry until smoke appears, grind both into powder. Mix with wine and take 1 qian to expel retained blood. If not stopped, take again; the effect is miraculous.

*Yanyi* states: Chen Cangqi and Rihua Zi have described Shuizhi thoroughly. The large ones in the capital are also called Ma Die; those with yellow abdomens are called Mahuang. They fear salt, yet they are effective in treating trauma. Neither the *Jing* nor the *Zhu* mentions processing methods; one must be careful and not neglect this. Current practitioners use stir-fried versions.