Secretin
Secretin was the first hormone to be identified. In 1902, William Bayliss and Ernest Starling were studying how the nervous system controls the process of digestion. It was known that the pancreas secreted digestive juices in response to the passage of food (chyme) through the pyloric sphincter into the duodenum. They discovered (by cutting all the nerves to the pancreas in their experimental animals) that this process was not, in fact, governed by the nervous system. They determined that a substance secreted by the intestinal lining stimulates the pancreas after being transported via the bloodstream. They named this intestinal secretion "secretin". Secretin was the first such "chemical messenger" identified. This type of substance is now called a hormone, a term coined by Bayliss in 1905.
Morphine
Morphine was discovered as the first active alkaloid extracted from the opium poppy plant in December 1804 in Paderborn, Germany, by Friedrich Sertürner. In 1817 Sertürner reported experiments in which he administered morphine to himself, three young boys, three dogs, and a mouse; all four people almost died. Sertürner originally named the substance "morphium" after the Greek god of dreams, Morpheus, as it has a tendency to cause sleep. Sertürner's morphium was six times stronger than opium. He hypothesized that, because lower doses of the drug were needed, it would be less addictive. However Sertürner became addicted to the drug, warning that "I consider it my duty to attract attention to the terrible effects of this new substance I called morphium in order that calamity may be averted."