"Sum" is the title of the chapter, and it describes the behavior of Cominio. He is cunning and vicious. He used to be a scary creature, but he has become more restrained. He likes to visit his boss at home, which is why there is nothing he can do about it. He tells the narrator that he has two cans of medicine, one for Samuel, and the other for the cat. The cat says he is fine, and that he should have had the medicine earlier. He says he scampers off like a "kicked puppy" . He also says that he treats other dogs and cats well, but that if something were to happen to him, he would not be able to return.