Abstract
Summary
The principle is espoused that even though effects on growth occur, changes in the quantity of body constituents which are accompanied by alterations in body nitrogen, fat and water contents may be evaluated on the basis of femur length. Linear ln-ln regressions may be derived with femur length as the independent variable. As an example of the application of this principle, mice were starved and refed, the carcass was dissolved in concentrated formic acid and total body nitrogen, potassium, calcium and formed creatinine were measured. Differences between observed values and values expected from femur length were determined. Decrement in potassium (meq), calcium (meq), and creatinine (mg) per g of nitrogen lost were respectively: 2.9, 2.4 and .13 (for losses of less 80 mg of nitrogen and .058 for losses greater than 80 mg of nitrogen). During re-feeding formed creatinine exceeded predicted values until continuation of growth occurred. Nitrogen, potassium, and calcium reached prestarvation values before growth continued.
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