Earwax from sheep that have eaten death camas contains ... zygacine and zygadenine, which cause mouth frothing, teeth grinding, twitching, stiff-legged walking, vomiting and potentially death ...

I noticed a large number of sheep's teeth encrusted with bright yellow tartar, identical in appearance with good average bright non-arsenical iron pyrites. I was assured that the sheep were fed ...

J. Lewis Abbott concerning the metallic-looking encrustation occurring on the teeth of sheep. In Proc. Linnean Soc. N.S. Wales (vol. 45, 1920, p. 324), abstracted in NATURE of April 21 last (p.