Yiquan (意拳; I Ch’uan) was founded by Wang Xiangzhai (王薌齋), master of Xingyiquan.
Yiquan is essentially formless, with no fixed movements or techniques, a distillation of the internal aspects at the core of all arts that Wang was exposed to, including Fujian hèquán, T’ai chi ch’uan, bāguàzhǎng, and Liuhebafa. Focus is on developing natural movement and perception of body through a system of concepts and training. Yiquan also differs from other eastern martial arts in its omission of concepts like qi, meridians, and dantianthe, the reason being that preconceptions block the understanding one’s true present nature.
Wang Xiangzhai studied Xingyiquan with Guo Yunshen in his childhood, then travelled China, comparing skills with masters of various styles of kung fu. By the mid-1920’s, he concluded Xingyiquan was often taught with too much emphasis on ‘outer form’, neglecting the essence of true power. He started to teach what he felt was the true essence of the art by removing Xing (form) from the name, and simply calling it Yiquan.
(Wikipedia, https://en.wikipedia.org/wiki/Yiquan)