The phrase "a gradual form" is correct and usable in written English.
It can be used to describe a process or change that occurs slowly over time, rather than suddenly or abruptly.
Example: "The artist's style evolved into a gradual form of abstraction, reflecting her changing perspective on the world."
Alternatives: "a slow process" or "a progressive manner".
When scientists started investigating BEN, they thought that it might be a gradual, cumulative form of lead poisoning.
The metamorphosis of whiteflies varies from the typical gradual form.
With future technological breakthroughs, these resources will probably enter a gradual exploitation phase, forming a critical supplement to our country's existing natural gas production; therefore continuous attention needs to be paid to them.
Collagen breakdown and aggressive cartilage loss is predominantly noted in the presence of immune complex deposition, whereas milder, more gradual forms of damage are seen in models driven by macrophage or T cell activation.
Sarah Taylor's innings showed a gradual return to form but it was the way England coped without Charlotte Edwards that was the most pleasing.
It seems obvious from here that the narrow-minded policies of the current government are basically a gradual, long-run form of national suicide — and that's bad for Jews everywhere, not to mention the world.
This theoretical shift enabled Darwin to bracket his earlier efforts to develop a causal theory of life, and focus instead on the means by which the dynamic force of population was controlled, and determine how this control on population worked out in company with the phenomenon of slight individual variation and changing conditions of life to produce a gradual change of form and function.
At issue here was whether the known fossil record displayed a gradual progression of forms from simple to complex, or whether it supported the claim for the persistence of major groups throughout the record as might be held by one in the tradition of Cuvier.
The move from the sociability that characterized upper-class culture in the 18th century to the more didactic, socially concerned interventions of the early and mid-19th century gave way to a gradual involvement in hitherto forbidden forms, forms now suitably sanitized and made rational (or, as in the case of classical music, made sacred).
There was, however, a gradual coarsening both of forms and of the decoration over the four centuries of production.
