Professor Hervé, of the School of Anthropology of Paris, has argued that the presence of the “Wormian bones” and the complexity of the cranial sutures are a measure of the rapidity of brain-development, and consequently a criterion of mental activity in a stock. This can scarcely be accepted, for we are not sure that the rapidity of bone-formation bears any ratio to the growth of the brain-cells; but it is not rash to argue that a people whose bones are largely diseased must have lived in unhygienic conditions, and had become degenerate in mind as well as body. Such is the case with the skeletons of that wholly unknown tribe who once densely peopled the Salt River valley in Arizona, and of those who dwelt near the great cemetery of Ancon in Peru. About one-third of the skeletons present pathological features indicating long-continued defective nutrition or widespread disease. No wonder that both stocks perished off the earth. Though at one time singularly advanced, they had sunk into complete degeneracy. _Muscular System; Height and Weight._—There is a relation between height, weight, and mental power, true for the individual and the group. This is not mysterious, as all three depend upon nutrition. Physiologists lay down ratios of height, weight, and age which are requisite to the highest health, mental and physical. We may go further, and say that any marked aberration from the average of the species in these respects is accompanied by some equally noticeable psychical peculiarity. Dwarfs have often acute minds, but rarely deep affections. Inferior stature is often an ethnic trait. The central African pygmies, the Lapps, and the Bushmen are familiar examples. Mr. Haliburton has recorded others in the Atlas and Pyrenean mountains; and Dr. Collignon reports the diminution in height in some districts of central France. The explanation of all is the same—lack of proper, regular, and sufficient alimentation. They are, as the Germans say, _Kümmerformen_, products of wretchedness. The shortest of the Bushmen are also the most miserable—those living amid the barren sands of the Kalihari desert. The reaction of such prolonged semi-starvation on the functions of the brain-cells leads to psychical dwarfishness. None of these undersized stocks have gained a position in history or contributed to the culture of humanity. They have been unequal in physical strife, and have been forced to the wall. _Reproduction._—The reproductive function in its various manifestations exerts an enormous influence on the individual mind, and exhibits broad racial and ethnic distinctions. Its power is scarcely less operative in the fate of nations than of persons, and its reflection in the mind of groups deserves closest attention.