Final answer:
The poem "From the Dark Tower" by Countee Cullen is written in the form of a Petrarchan sonnet. Cullen uses this structure to express the challenges faced by African-American poets.
Step-by-step explanation:
The poem "From the Dark Tower" by Countee Cullen is written in the form of a Petrarchan sonnet. The Petrarchan sonnet consists of an octave, which presents a problem or challenge, and a sestet, which resolves or comments on the problem. Cullen applies this structure to express his message by presenting the challenges faced by African-American poets in the octave and providing a resolution or commentary in the sestet.