. The origin and evolution of life, on the theory of action, reaction and interaction of energy. olichocephaly) and the broadhead-form (brachycephaly), orthe long-fingered form (dolicho-dactyly) and the short-fingeredform (brachydactyly), whichhave been interpreted as con-genital characters appearing atbirth and tending to be transmitted to offspring. Brachy-dactyly may be transmitted through several generations, butuntil recently no one has suggested what may be its possiblecause. It has now been found^ that both the short-fingered con-dition (brachydactyly) and the slender-fingered condition
. The origin and evolution of life, on the theory of action, reaction and interaction of energy. olichocephaly) and the broadhead-form (brachycephaly), orthe long-fingered form (dolicho-dactyly) and the short-fingeredform (brachydactyly), whichhave been interpreted as con-genital characters appearing atbirth and tending to be transmitted to offspring. Brachy-dactyly may be transmitted through several generations, butuntil recently no one has suggested what may be its possiblecause. It has now been found^ that both the short-fingered con-dition (brachydactyly) and the slender-fingered condition maybe induced during the lifetime of the individual in a previouslyhealthy and normal pair of hands by a diseased or injured con-dition of the pituitary body at the base of the brain. If the 1 Gushing, Harvey, 1911, pp. 253, 256. Fig. 119. Result of Removing theThyroid and Parathyroid Glands. (Right.) Normal sheep fourteen monthsold. (Left.) A sheep of the same age fromwhich the thyroids and parathyroidswere removed twelve months previ-ously. After Sutherland Simpson. MODES OF EVOLUTION 251. Fic. 120. secretions of the pituitary are abnormally active (hyperpitui-tarism) the hand becomes broad and the fingers stumpy (, B). If the secretions of the pituitary are abnormally re-duced (hypopituitarism) the fingers become tapering and slender(Fig. 118, C). Thus in a most remarkable manner the internalsecretions of a very ancientductless gland, attached to thebrain and originating in theroof of the mouth in our mostremote fish-like ancestors, affectthe proportions both of fleshand bones in the fingers, aswell as the proportions of manyother parts of the body. Whether this is a mere co-incidence of a heredity-chro-matin congenital characterwith a mere bodily chemicalmessenger character it wouldbe premature to say. It cer-tainly appears that chemical in-teractions from the pituitary body control the normal and ab-normal development of proportions in distant parts of the body. Ch
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