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 and What Should Never Be" was performed live at Led Zeppelin concerts between 1969 and 1973. A live version taken from a performance at the Royal Albert Hall in 1970 can be seen on the "Led Zeppelin DVD". Another was included on disc two of the live triple album "How The West Was Won". Two more versions were included in BBC Sessions. 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