what's orthogenetic?

it's a principle that attempts to explain development--specifically how systems self-organize.

One particular good quote that sums this prinicple comes from Werner in 1957:

"Developmental psychology postulates one regulative principle of development; it is an orthogenetic principle which states that wherever development occurs it proceeds from a state of relative globality and lack of differentiation to a state of increasing differentiation, articulation, and hierarchical integration."