1) Adult female mongrel dogs were employed as subjects. These experimental animals were divided into four groups: Untreated, adrenaline injected, atropine injected, and vagotomy group. Each group was given the same surgical stress.
2) In the untreated group, neurosecretion was found to be remarkable after the stress.
3) In the adrenaline and atropine injected group, and the vagotomy group, neurosecretion by the stress was suppressed.
4) Action current of the vagus nerve showed that the parasympathetic nerves are markedly stimulated by the stress.
5) Acetylcholine is discharged by the stress in the neurohypophysis at first, and later appears in the hypothalamus.
6) According to these findings, it is concluded that the vagus nerve is stimulated by the surgical stress, then acetylcholine is liberated in the neurohypophysis, and thereafter in the hypothalamus. Neurosecretion follows thereon.