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.
Alma Joslyn Whiffen-Barksdale
In 1955, Barksdale became a Research Associate at the New York Botanical Garden and returned to the study of aquatic fungi. From 1955 to 1961, she expanded existing research on the species "Achlya bisexualis", focusing on the fungus' unique sexual reproductive hormones. It had been previously concluded by fellow mycologist, Dr.John Raper, that the development of sexual organs in "A. bisexualis" was mediated by the exchange of hormones between the male and female strains of the fungus. Over the course of 10 years of research, Dr. Barksdale discovered and isolated the sex hormone antheridiol: a steroid released by the female strains of "A. bisexualis", which stimulates the growth of antheridia when introduced to male strains of the fungus. Antheridiol also stimulates the release of a second hormone, when introduced to the male strains, which promoted the growth of oogonia in the female strains. Her discoveries sparked a new wave of interest in the Achlya genus as a research subject over the following decades, and she and Dr. Raper are jointly considered the primary establishing figures in "Achlya" research, according to the retrospective on her life published in the 1981 issue of "Achlya Newsletter."