As if in reply to my appeal he commenced to utter hoarse convulsive sounds which resembled nothing so much as the barking of a dog, and began a sort of hideous writhing in a circle about the room. I bent and seized him by the shoulders. Violently, desperately, I shook him. He turned his head and snapped at my wrist. I was sick with horror, but I dared not release him for fear that he would destroy himself in a paroxysm of rage.