"The method involves considering organisms as life cycles, and each life cycle is made up of a series of chemical reactions termed steps. The steps occur together in an organized sequence, and they are often grouped together in chains which are to varying degrees dissociable from one another. The life cycle has a point of minimum size and a point of maximum size. The point of minimum size is the cell (either a zygote or spore), and this furthermore is the minimum connection, the minimum unit of inheritance from one life cycle to the next. The process of reaching the point of maximum size is usually referred to as development, and it has the largest magnitude of steps and chains in the whole cycle. The point of maximum size is also the point where innovations or variations are introduced, while the point of maximum size is the point where the organism becomes capable of reproduction, and if this is prevented the elimination of variants is achieved. Since natural selection involves both the introduction of new variations and the constant culling of different variants, the life cycle is in this sense the unit of evolution. Because the life cycle is one complete set of steps (before the repetition occurs in the next cycle) and because it is the unit which permits natural selection to occur, it is the connecting device, the hook, that joins molecular and evolutionary events"--Page 199.