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Cang'erzi grass (Xanthium strumarium), during the transition between summer and autumn, after rainy weather, develops worms inside its moldy stems. These worms are taken out, dried on a warming stove, stored in small bamboo tubes for carrying, or kept in tin bottles to prevent gas leakage. For patients suffering from Ding poison (a type of severe skin infection/abscess), the worm is ground into fine powder, applied onto plasters specifically used for treating Ding sores, and patched over the lesion. After one night, the sore is extracted and healed. (Before application, the head of the sore should be gently pricked with a needle to drain pus.) While I was in Taizhou, my servant Zhou Jin cultivated Cang'erzi grass across entire fields; using the worms to save people yielded miraculous effects repeatedly. Later, near the schoolhouse in Hangzhou prefecture, there were many Cang'erzi worms; they were effective in treating Ding sores without exception. My fellow townsman, Scholar Zheng Zhuoyan (courtesy name Fengqiang), took them to Kaihua and also saved several people there. Since that area lacked Cang'erzi grass, he wrote to request seeds for propagation. Additionally, Qinghao worms (worms from Artemisia annua) are most efficacious in treating pediatric convulsions (Jingfeng). My grandson Ronglin once relied on this method to survive. Both prescriptions are recorded in *Bencao Gangmu* (Compendium of Materia Medica), yet their efficacy is rarely known by the world today; thus, I record them here. (Qinghao worms are also dried in the stem, ground into powder, mixed with ash from Juncus effusus (Dengxin Cao), and administered with decoction.)

(Bingzhang) Note: Cang'erzi worms not only have special effects on treating Ding sores but are also effective for any Yang abscess (Yang Yong) that has become red, swollen, and purulent. Placing one such worm on the top of the wound, covered externally with a cooling plaster for eight hours, allows the toxin to be "bitten through." I usually collect these in August and September, preserve them in sesame oil for future use, as they can replace surgical knives and needles; truly a miraculous effect.

The water in Hangzhou city is turbid, so households all draw spring water from the sky (rainwater). Over time, it often breeds mosquito larvae (Zijue worms). *Yi Zhai Za Zhuo* states that water collected from dawn until sunset is "Yang" water, while that collected from sunset until before rooster crow is "Yin" water. If Yin and Yang waters are kept in separate vessels, since "isolated Yin does not generate, and isolated Yang does not grow," there will naturally be no problem with mosquito larvae. Hu Zihui of Jingxian County, in *Zi Guan Fu Yan*, also stated that rain before noon belongs to Yang, and rain after noon belongs to Yin. Water of "isolated Yang" can be used to fertilize goldfish eggs. (Bingzhang) Note: Sky water breeding mosquito larvae is mostly due to long-term accumulation or unclean water quality. Rainwater immediately following a long dry spell inevitably washes down accumulated dust from roofs; this initial runoff should be discarded outside the vat. Only after the subsequent clean rain falls should it be collected in the vat. The turbid sediment at the bottom of the water vat should be regularly suctioned out using a siphon tube to keep the water clean, thereby eliminating this drawback.