If you recall in paragraph 25 killing a snake is a grown mongoose's business. This is his first step to growing up. Also if his mother fed him on snake, he would have natural eaten it. Now, since he had other snakes to fight, he didn't eat the snake. This shows how he has grown up. In paragraph 56 and 57, he is trying figure out when he should kill Nag. Paragraph 57 says, "'Now, if I kill him here, Nagaina will know; and if I fight him on the open floor, the odds are in his favor. What am I to do?' said Rikki-tikki-tavi." When Rikki-tikki attacked Karait he just attacked he didn't think about anything. That time he put himself at a bigger risk. This time he actually spent time to think. He considered his options and his surroundings. This shows that he has grown a little more. In paragraph 61 he kills Nag. In paragraph 104 he kills Nagaina. Paragraph 104 says, "...Rikki-tikki, covered with the dirt, dragged himself out of the hole leg by leg, licking his whiskers." He had just gone the rat-hole with his teeth in Nagaina. When he came back up, the garden found out that he killed Nagaina. When it says that he licking his whiskers, I can infer that he might have eaten…