The starved ones will be unable to find their way out, whereas the others will have little or no difficulty in getting out. Their dispositions can be altered by mineral feeding. A cage of normal rats will live in amity. Restrict their calcium, and they will become irritable and draw apart from one another. Then they will begin to fight.
Many backward children are stupid merely because they are deficient in magnesia.
We punish them for our failure to feed them properly. Certainly our physical well-being is more directly dependent upon the mineral we take into our systems than upon calories or vitamins or upon the precise proportions of starch, protein, or carbohydrates we consume. It is now agreed that at least 16 mineral elements are indispensable for normal nutrition, and several more are always found in small amounts of the body, although their precise physiological role has not been determined. Of the 11 indispensable salts, calcium, phosphorus, and iron are perhaps the most important. More than one-third had defective vision, round shoulders, bow legs, and anemia.