Phylogeny and ontogeny are, therefore, the two coordinated branches of morphology. Phylogeny is the developmental history [Entwickelungsgeschichte] of the abstract, genealogical individual; ontogeny, on the other hand, is the developmental history of the concrete, morphological individual.
![Phylogeny and ontogeny are, therefore, the two coordinated branches of morphology. Phylogeny is the developmental history [Entwickelungsgeschichte] of the abstract, genealogical individual; ontogeny, on the other hand,](http://cdn.quoteddaily.com/images/ernst-haeckel/phylogeny-and-ontogeny-are-therefore-the-two-coordinated-branches-of-morphology-phylogeny-is-the-developmental-history-entwickelungsgeschichte-of-the-abstract.jpg)