49:5.19

3. Spirit-reception series. There are three groups of mind design as related to contact with spirit affairs. This classification does not refer to the one-, two-, and three-brained orders of mortals; it refers primarily to gland chemistry, more particularly to the organization of certain glands comparable to the pituitary bodies. The races on some worlds have one gland, on others two, as do Urantians, while on still other spheres the races have three of these unique bodies. The inherent imagination and spiritual receptivity is definitely influenced by this differential chemical endowment.