Dunbar stopped as if he meant to say no more, and Tom became apologetic.
“Won’t you please go on, Mr. Dunbar? I’m sorry I interrupted.”
“Oh, but you must interrupt. If you don’t interpose with questions, how am I to know whether I’ve made my meaning clear or not? And how am I to know what else you wish to hear? No, no, no. Don’t withhold any question that comes into your mind, or I shall feel that I’m making a bore of myself by talking too much.”
“You spoke,” said Dick, “of certain fishes that are exceptions to the rule.”
“Oh, yes; thank you. I meant to come back to that but forgot it. The chief exception I know of is the bullhead, a small species of catfish that abounds in northern waters, particularly in the Adirondack lakes. The bullhead has gustatory nerves all over him. He can taste with his tail, or his side, or his head, as well as with his mouth. Of course there’s a good reason for the difference.”
“I suppose so, but I can’t imagine what it is,” said Larry.
“Neither can I,” echoed Tom and Dick. Cal continued the silence he had not broken by a word since Dunbar had begun. Observing the fact, Dick was troubled lest his playful suppression of Cal at the beginning had wounded him. So, rising, he went over to Cal’s side, passed his arm around him in warm friendly fashion, and said under his breath:
“Did you take me seriously, Cal? Are you hurt or offended?”
“No, you sympathetically sublimated idiot, of course not. It is only that I want to hear all I can of Mr. Dunbar’s talk. You know I’ve always been interested in fish—even when they refuse to take bait. Hush. He’s about to begin again.”
“Oh, it is obvious enough when you think about it,” said Dunbar. “It is a fundamental law of nature that every living thing, animal or vegetable, shall tend to develop whatever organs or functions it has need of, for defense against enemies or for securing the food it needs. You see that everywhere, in the coloring of animals and in a thousand other ways. The upper side of a flounder is exactly the color of the sand on which he lies. That is to prevent the shark and other enemies from seeing him and eating him up. But his under side, which cannot be seen at all by his enemies, is white, because there is no need of color in it. I could give you a hundred illustrations, but there is no need. Your own daily observation will supply them.”