Final answer:
The phrase in question suggests the motif of physiology, as it deals with biological development and the inheritance of complex structures such as the eye and brain.
Step-by-step explanation:
The line "I saw how the worm inherited the wonders of the eye and brain" implies a motif of physiology. A motif in literature is a recurring element that has symbolic significance in a story. In this case, the reference to the worm inheriting the complexities of the eye and brain suggests a deeper exploration of biological development and evolution, which are key aspects of physiology. The observation of a simple organism like a worm developing sophisticated organs leads to discussions about the nature of inheritance, the progression of biological complexity, and perhaps the marvels of the natural world.