Note 383 — Chapter XIV

"This theory (evolution) shows that what was formerly called 'structural plan' or 'type' is the sum of the dispositions (Einrichtungen) of the animal organisation which are perpetuated by heredity, while it explains the modifications of these dispositions as adaptive states. Heredity and adaptation are thus the two important factors through which both the unity and the variety of organisation can be understood" (Grundzüge, p. 19).