In the well-known Jewett edition, this is the sentence that describes Eliza in chapter 1, when she arrives in the room to retrieve her son Harry from Shelby and Haley, and the slave trader sizes her up as merchandise.
There was the same rich, full, dark eye, with its long lashes; the same ripples of silky black hair. The brown of her complexion gave way on the cheek to a perceptible flush, which deepened as she saw the gaze of the strange man fixed upon her in bold and undisguised admiration.
In the National Era, rather than two sentences, there is one:
There was the same rich, full, dark eye, with its long lashes, the same ripples of silky black hair; the brown of her complexion gave way on the cheek to a perceptible flush, which deepened as she saw the gaze of the strange man fixed upon her in bold and undisguised admiration.
The differences are the comma (Era) or semicolon (Jewett) after the word lashes and the semicolon (Era) or period (Jewett) after the word hair. The purpose of the description, in either style of punctuation, shifts between Eliza’s appearance as echoing little Harry’s (same eye, lashes, hair) and Eliza’s value in Haley’s eye as a “fine female article,” as next sentence reiterates.
In my thinking, the Era version, is much more effective, as her appearance (formerly within context of being Harry’s mother) is re-contextualized entirely by Haley’s gaze into sexual chattel, because it is one sentence: eye, lashes, hair–her Harry’s-mother qualities–have their polarities reversed. In the Jewett edition, with two, the link between Eliza as mother and chattel is attenuated, as Eliza’s embarrassment rises to the fore to counter-act Haley’s gaze, to separate it from the description of her as Harry’s mother. There are two sentences, a “Harry’s mother” sentence and a “Haley’s gaze” sentence.
The key phrase is “brown of her complexion gave way on the cheek to a perceptible flush,” and the reader has two possibilities for why that is happening. When one sentence, in the Era, the reader may be lulled into assuming that she is still Harry’s mother, her embarrassment arising because of her child’s antics. When two sentences, her flush (embarrassment) is more likely to arise because she recognizes Haley’s gaze upon her.
Whether the flush on her face is visible to Haley’s gaze is highly significant in the nineteenth century because a conventional racist tropes is that black people lack embarrassment, because the flush of embarrassment is one of the marks of highly refined sensibility. The racist gaze denies the possibility that refined sensibility is visible on the black face. Eliza, of mixed race parentage, has skin light enough to pass as white, and her desirability (within this conventionally racist trope, having white-like features) raises her monetary value as a sex slave.
When the reader views Eliza’s flushed face from both directions–as one does more readily in the Era–her transition from mother to sexual chattel is even more devastating. That’s why punctuation, which doesn’t matter, might matter.