Prothoracicotropic hormone
Prothoracicotropic hormone (PTTH) was the first insect hormone to be discovered. It was originally described simply as "brain hormone" by early workers such as Stefan Kopeć (1922) and Vincent Wigglesworth (1934), who realized that ligation of the head of immature insects could prevent molting or pupation of the body region excluded from the head if the ligation was performed before a critical age in the lifestage was reached. After a certain point the ligation had no effect and both sections of the insect would molt or pupate. However, implantation of a conspecific brain to a sessile ligated abdomen or an abdomen under diapause would induce molting or pupation. Thus, the brain was originally thought to be the source of the hormone that induces molting in insects.
David Landsborough Thomson
David Landsborough Thomson F.R.S.C., (1901 - 1964) was a Canadian biochemist, best known for the co-discovery of Adrenocorticotropic hormone (adreno-cortical thyroid hormone or ACTH) and as the vice-principal of McGill University. ACTH was co-discovered by Evelyn M. Anderson, James Bertram Collip and Thomson. In a paper published in 1933, they explained its function in the body.