The inheritance of complexes is of great interest. The manner in which this arises on a Mendelian hasis can he most easily seen by the consideration of a simple case. Let two races of different stature mix in equal numbers. Let for simplicity stature depend on two elements (a, a), (c, c) in one race, and on (b, b), (d, d) corresponding elements in the other. Then the permanent race obtained by free mating without any special selection of one parent or another will consist of the following proportions:—

Now two factors may come into play: either dominance may not exist and the hybrid be a blend, or, on the other hand, dominance may determine the result of the mating. If dominance does not exist we may rearrange the elements according as they contain one or more element from each original race.