The weak parts of this story are the sudden and unexplained departure of the Simons; the subsequent useless cruelty of treating the child like a wild beast and keeping him in a dark room practically out of sight (unless any doubt of his identity was possible), while his sister was in comparative comfort; the cause of death, declared to be of long standing, but in fact developed with such rapidity; the insufficient excuse provided for the child's muteness under Gomin's regime (he had answered Barras) and the irregularities in the formalities in attending the death and the funeral, when a simple identification of the body by Marie Therese would have prevented any question of resuscitated dauphins.
I know that, to the common apprehension, this phenomenon of whiteness is not confessed to be the prime agent in exaggerating the terror of objects otherwise terrible; nor to the unimaginative mind is there aught of terror in those appearances whose awfulness to another mind almost solely consists in this one phenomenon, especially when exhibited under any form at all approaching to muteness or universality.
By night the same muteness of humanity before the shrieks of the ocean prevailed; still in silence the men swung in the bowlines; still wordless Ahab stood up to the blast.
The boy seemed attentive in spite of his muteness so Dean resumed sweeping up needles with his hand and continued to chatter.
My guess is Donnie's muteness may be far more complicated.