Why are geckos also called palace guards?

According to the Natural History of Jin Dynasty, if you feed the gecko with cinnabar, the gecko will turn red all over. After eating seven kilograms of cinnabar, mash the gecko and dye the limbs of the Virgin with it, so the color will not fade.

Only after sexual intercourse, its color will fade, so it is called "palace sand"

Extended data:

Shougong Sha is a female chameleon made in China, which was called Zhu Gong in ancient times. In its breeding season, it is captured and mashed and mixed with cinnabar.

Modern science has confirmed that female chameleons are full of estrogen in reproductive period. When it meets androgen, estrogen and androgen will neutralize and disappear.

Tao Hongjing, a famous doctor in the Liang Dynasty, said: When I was guarding the palace, I liked to hedge the wall and feed it with Zhu, which was three pounds. When I kill it, I will draw a woman's body. If there is a handover, I will take it off; No, it's like a red ambition, so it's named Shougong. This Jin Gong Wei refers to the chameleon.

References:

Gongsha-Baidu Encyclopedia