Figure 40 gives the composition of the yolk and white taken together, and of the yolk and white separated. The protein content is high, and the fat content as well, the yolk containing a higher percentage of these two foodstuffs than the white. The mineral matter is of high value, iron and phosphorus being found in ideal forms in the yolk. In using the egg as food we are availing ourselves of one of nature's richest storehouses. A single egg of average size yields about 75 calories, of which 60 come from the yolk and 15 from the white. A very large egg, weighing two and two thirds ounces, will yield 100 calories.