The transparency of salt water has long been recognized. Its clarity is believed to exceed that of spring water. The mineral and organic substances it holds in suspension actually increase its translucency. In certain parts of the Caribbean Sea, you can see the sandy bottom with startling distinctness as deep as 145 meters down, and the penetrating power of the sun’s rays seems to give out only at a depth of 300 meters. But in this fluid setting traveled by the Nautilus, our electric glow was being generated in the very heart of the waves. It was no longer illuminated water, it was liquid light. If we accept the hypotheses of the microbiologist Ehrenberg—who believes that these underwater depths are lit up by phosphorescent organisms—nature has certainly saved one of her most prodigious sights for residents of the sea, and I could judge for myself from the thousandfold play of the light. On both sides I had windows opening over these unexplored depths. The darkness in the lounge enhanced the brightness outside, and we stared as if this clear glass were the window of an immense aquarium. The Nautilus seemed to be standing still. This was due to the lack of landmarks. But streaks of water, parted by the ship’s spur, sometimes threaded before our eyes with extraordinary speed. In wonderment, we leaned on our elbows before these show windows, and our stunned silence remained unbroken until Conseil said: “You wanted to see something, Ned my friend; well, now you have something to see!” “How unusual!” the Canadian put in, setting aside his tantrums and getaway schemes while submitting to this irresistible allure. “A man would go an even greater distance just to stare at such a sight!” “Ah!” I exclaimed. “I see our captain’s way of life! He’s found himself a separate world that saves its most astonishing wonders just for him!” “But where are the fish?” the Canadian ventured to observe. “I don’t see any fish!” “Why would you care, Ned my friend?” Conseil replied. “Since you have no knowledge of them.” “Me? A fisherman!” Ned Land exclaimed. And on this subject a dispute arose between the two friends, since both were knowledgeable about fish, but from totally different standpoints. Everyone knows that fish make up the fourth and last class in the vertebrate branch. They have been quite aptly defined as: “cold-blooded vertebrates with a double circulatory system, breathing through gills, and designed to live in water.” They consist of two distinct series: the series of bony fish, in other words, those whose spines have vertebrae made of bone; and cartilaginous fish, in other words, those whose spines have vertebrae made of cartilage. Possibly the Canadian was familiar with this distinction, but Conseil knew far more about it; and since he and Ned were now fast friends, he just had to show off. So he told the harpooner: