Found in egg yolk, brain, bile, in cadavers. Formed during putrefaction by dehydration of choline: Hofmann, Compt. Rend. 47, 559 (1858); Renshaw, Ware, J. Am. Chem. Soc. 47, 2992 (1925). Prepn: Meyer, Hopff, Ber. 54, 2277 (1921); from aq trimethylamine and acetylene: Gardner et al., J. Chem. Soc. 1949, 789. Separation and identification in biological fluids: E. Merlevede et al., Arch. Int. Pharmacodyn. 122, 474 (1959). Stereoelectronic config: Intern. Kongr. Entomol. Verhandl., 11th, Vienna, 1960, No. 3, pp 87-93, C.A. 57, 7749b (1962). Toxicity study: Hunt, J. Pharmacol. Exp. Ther. 28, 267 (1926).