  This paper concerns the model theory of jet spaces (i.e., higher-order
tangent spaces) in differentially closed fields. Suppose p is the generic type
of the jet space to a finite dimensional differential-algebraic variety at a
generic point. It is shown that p satisfies a certain strengthening of almost
internality to the constant field called "preserving internality to the
constants". This strengthening is a model-theoretic abstraction of the generic
behaviour of jet spaces in complex-analytic geometry. A counterexample is
constructed showing that only this generic analogue holds in
differential-algebraic geometry.
