Alkaloid ("Agonopterix alstroemeriana)." This moth feeds on its highly toxic and alkaloid-rich host plant poison hemlock ("Conium maculatum") during its larval stage. "A. asltroemeriana" may benefit twofold from the toxicity of the naturally-occurring alkaloids, both through the unpalatability of the species to predators and through the ability of "A. alstroemeriana" to recognize "Conium maculatum" as the correct location for oviposition. Medical use of alkaloid-containing plants has a long history, and, thus, when the first alkaloids were isolated in the 19th century, they immediately found application in clinical practice. Many alkaloids are still used in medicine, usually in the form of salts,
What Is and What Should Never Be What Is and What Should Never Be "What Is and What Should Never Be" is a song by English rock band Led Zeppelin. It was written by Jimmy Page and Robert Plant and was included as the second track on "Led Zeppelin II" (1969). "What is and What Should Never Be" was one of the first songs on which Page used his soon-to-become trademark Gibson Les Paul for recording. The production makes liberal use of stereo as the guitars pan back and forth between channels. Robert Plant's vocals were phased during the verses. Record producer Rick Rubin has remarked, "The