Why do you think Mme. Aubain shakes slightly when she sees Félicité respond to the news of her nephew's death?

Mme. Aubain's reaction to Victor's death is surprising given her past inability to recognize the value of Félicité's feelings. When she reads the letter to Félicité that tells her of Victor's death, she does seem to feel that the news is going to be very difficult for her. This occurs shortly after she has begun to be worried about her own daughter and shortly after Félicité's attempt to sympathize with her by relating her daughter to her nephew. Perhaps she shakes because she sees Félicité's real emotions and, for the first time, shares them with her. Or, perhaps she shakes because she feels like Victor's death might be a bad omen with respect to her own daughter.