a small, somewhat
conical structure in the
brain. It secretes various chemical substances and appears to function in various animals as a light-sensing organ, as a biological
clock, or a ductless gland whose secretions regulate the activity of
sex glands.
a small, somewhat
conical structure in the
brain. It secretes various chemical substances and appears to function in various animals as a light-sensing organ, as a biological
clock, or a ductless gland (
endocrine gland) whose secretions regulate the activity of
sex glands.