The idea had been suggested that the factors which determine the future character might be ferments or enzymes, or substances from which such ferments develop. A. R. Moore[210] pointed out that the cross-bars in the skeleton of the hybrid between _S. purpuratus_ and _franciscanus_ develop more slowly than in the pure breed and that this should be expected if the determiners were enzymes. Since the pure _purpuratus_ has two determiners for the development of the cross-bars (from both egg and sperm), the hybrids only one (from either egg or sperm), the pure _purpuratus_ should have twice the enzyme mass of the hybrid. It is known that the velocity of a chemical reaction increases in proportion with the mass (or in some cases in proportion with the square root of the mass) of the enzyme; the cross-bars should therefore develop faster in the pure than in the hybrid breeds, as was observed by Moore. It was, however, not possible to obtain quantitative data. [210] Moore, A. R., _Arch. f. Entwcklngsmech._, 1912, xxxiv., 168. On the other hand, it is obvious that this reasoning would not hold for all cases. Thus when beans with violet flowers are crossed with white-flowered beans the hybrids are pale blue, which indicates that the hybrids have less pigment than the pure violet. Now we know that the mass of enzyme does not influence the chemical equilibrium but only the velocity of the reaction. The hybrids and pure violets differ, however, in the mass of violet pigment formed, that is to say, in regard to the equilibrium. Hence the idea that the determiners are enzymes or give rise to enzymes is probably not applicable to cases of this type.