Later, after school started up, Henrietta showed those who continued in the club the five-spotted sphinx moths hatching out. The students sketched the black-encircled orange spots ornamenting each side of the torso and the soft gray back of the head. Mandy rendered the velvety eyes, but it was Hester, joining the youngsters, who captured the five-inch tongue unrolling and being shaken and then smoothed, like a lock of hair, before recurling into a little wheel. Later, after they released the moths, they found one making a sound like a tiny drill as it drank from a stand of evening primroses.

“That’s not a hummingbird?” Hester said, leaning in.

“Hummingbird moth,” Henrietta said. “Watch.” Four inches from the next flower the creature hovered—not dipping a long beak in for the nectar, but instead unfurling that marvelous tongue. Hester was so pleased by this that she volunteered to help once more in the spring of 1892, although she was pregnant again.

HENRIETTA KEPT HER worries to herself as Hester moved serenely through the months. Through June and July Hester collected and labeled caterpillars; in August and September she watched over the emerging moths and made sure they were mated before they laid their eggs. When Ambrose questioned her devotion, Hester swore that the atmosphere in the caterpillar room kept her healthy. At night, she told Henrietta, she sometimes wrapped her arms around her thickening torso and imagined her own body as a kind of sturdy pupa.

Was she joking? Henrietta, secretly appalled by that image, could not see even the trace of a smile on her sister’s face. With one hand Hester cradled the swelling that was just beginning to show. No more lifting, bending, kneeling after that; Henrietta brought an armchair in for her sister, watched over her anxiously, and often went to her house in the evening to tend to the housework she didn’t want Hester to do. When the being inside moved visibly beneath the taut cloth of Hester’s dress, Henrietta tried not to imagine it bursting out.

Everything about the birth went easily, though. The snow sifted peaceably down to the frozen lake. The chickens roosted without complaint. While Henrietta helped the midwife, their mother sat near Hester’s head and held her hand and Ambrose paced between the leafless apple trees. A few hours later Marion emerged, slick and wet and perfect. It was horrible to see her sister in pain, and yet to watch everything working as it should—a process she had seen before in cows and sheep and dogs, but never in a human—was also thrilling. Afterwards Henrietta brought her mother home and returned to find Hester and Marion already safely asleep.