The discovery, proof and reproof of neurosecretion (Speidel, 1917; Scharrer and Scharrer, 1934).

Seventeen years before the Scharrers demonstrated neurosecretory activity of neurons within the brains of vertebrates and invertebrates and convinced the scientific world of the existence of a neuroendocrine system, Carl Caskey Speidel (1917) had identified glandular neurons in the spinal cord of the skate, postulated a neurosecretory function, and performed experiments to prove his hypothesis. The correct conclusions that he formulated from morphologic observations were not believed by biologists until 'proved' by the Scharrers, who acknowledged his pioneering contributions. The Scharrers studied many species and even demonstrated neurosecretion in nemertine worms, now believed to be closely related to the ancestors of all vertebrates. Evolutionary theorists had speculated on neuroglandular function as early as 1900, and the contribution of comparative neuroanatomists to this field have resulted in a major medical advance.