Allometry formula: a cellular model.

The simple allometry formula y = bxk is often used to describe the relative growth of two parts X and Y of an organism. The allometric constant b can be usefully identified with the relative number of cell division centers (germinal centers) of the two parts, and the allometric constant k can be usefully identified with the relative frequency of cell division of the two parts. This approximation leads to experimentally testable predictions: for example, the developing brains of mammals and birds may have germinal centers not present in the developing brains of fish and reptiles, and the developing brains of humans may differ from the developing brains of monkeys in their rates of cell division.