H | N C / \ / \ / \ | | | / \ | | | H_{2}C CH-CH=CH_{2} \ / \ / | | CH-CHOH-HC CH_{2} \ / N Quinine =Strychnine=, C_{21}H_{22}N_{2}O_{2}, =brucine=, C_{21}H_{20}(OCH_{3})N_{2}O_{2}, and =curarine= are three alkaloids which are present in the seeds of several species of _Strychnos_. They are all highly poisonous. Beyond the fact that when they are hydrolyzed they yield quinoline and indole, their composition is unknown. =Morphine=, C_{17}H_{19}NO_{3}, is the chief alkaloid of opium, which is the dried juice of young pods of the poppy. Both the alcoholic solution of opium (known as "laudanum") and morphine itself are extensively used in medicine as narcotics to deaden pain. Morphine has an exceedingly complex structure, being a combination of an isoquinoline and a phenanthrene nucleus, which is probably correctly represented by the following formula: H H_{2} | ║ C C // \ / \ HOC C CH_{2} | ║ | C C N-CH_{3} / \\/ \ / / C CH O | | \ HC CH_{2} \ / \ / HC C | ║ H_{2}C CH \ / C ║ H_{2} =Codeine=, C_{17}H_{18}(OCH_{3})NO_{2}, which is also found in opium, is a methyl derivative of morphine. =Papaverine=, =laudanosine=, =narcotine=, and =narceine= are four other alkaloids found in opium. They each contain an isoquinoline nucleus, combined by one bond to a benzene ring, with one or more methyl groups and three or more methoxy (OCH_{3}) groups attached at various points around the three characteristic rings. The following formula for laudanosine will illustrate their structure: