It is no mere coincidence that inferiority of physique should be thus universally and inseparably associated with inferiority of economic condition. It is not a mere coincidence that superiority of physique should be generally associated with mental superiority. Nor will the suggestion of coincidence suffice to explain the universal association of low physical and mental development with criminal propensities. These facts possess a very definite, and very obvious, relation as cause and effect. The three main divisions of degeneracy, physical, mental, and moral, are inseparable and spring from the same causes. From the investigations which have been made in this country and from the voluminous literature upon the subject which similar investigations in European countries have produced, I am satisfied that poor, defective nutrition lies at the root of the physical degeneration of the poor; and _a priori_ reasoning would justify the conclusion that the mental degeneracy evidenced by the enormous number of backward children, educational failures, and the moral degeneracy evidenced by increasing juvenile delinquency and crime, are due to the same fundamental cause. From those data alone we might, with ample justification, adopt the words of a famous authority and say, “Defective nutrition lies at the base of all forms of degeneracy.”[71] We need not, however, rely upon this method, for there is no lack of direct testimony to show that low nutrition is the prime and most fruitful cause of mental dulness and its attendant evils. I do not wish to be understood as contending that physical, mental, or moral defects never exist except as a result of defective nutrition, or that malnutrition never exists except as a result of poverty. I know, for instance, that a great many children are backward in their studies because they are handicapped by defects of vision or hearing, adenoid growths, and the like. These are often easily curable, and the fitting of proper glasses, or the removal of adenoid growths by slight surgical operations, suffice to bring such children up to the standard of normality. In an examination of over 7000 children in New York public schools one-third were found to have “defects of vision, interfering with the proper pursuit of their studies.”[72] In such cases malnutrition may or may not be the initial cause. That defective vision is often attributable to low and improper nutrition is beyond question. My contention is that the vast majority of dull and backward children, whose number makes a serious pedagogical problem, and a still more serious social problem in that so many of them become either inefficient and dependent, or criminal, are dull and backward as a result of physical inferiority directly traceable to poor and inadequate feeding.