Robert, who had at first listened with only half an ear, like a person who merely expects to be bored, now made no attempt to interrupt. His attention delighted Lilian, who took it as a compliment to her lover. “You ought to tell us,” said she, “of what you were saying the other day about fish and their power of accommodation to the different amounts of salt in the sea.... That was it, wasn’t it?” “Except for certain regions,” went on Vincent, “the sea’s degree of saltness is pretty constant; and marine fauna as a rule tolerates only very slight variations of density. But the regions I was telling you about are nevertheless not uninhabited; the regions I mean are those which are subject to intense evaporation and in which, therefore, the proportion of water to salt is greatly reduced--or, on the contrary, those where the constant inflow of fresh water dilutes the salt and, so to speak, un-salts the sea--those that are near the mouths of great rivers, or such enormous currents as the Gulf Stream. In such regions the animals called _stenohaline_ grow enfeebled to the point of perishing; and as they become incapable of defending themselves, they inevitably fall a prey to the animals called _euryhaline_, so that the _euryhalines_ live by choice on the confines of the great currents, where the density of the water varies and where the _stenohalines_ meet their death. You understand, don’t you, that the _stenos_ are those which can exist only in water whose degree of saltness is unvarying; whilst the _eurys_....” “Are the pickles,” interrupted Robert,[3] who always referred everything back to himself, and only took an interest in that part of a theory which he could turn to account. “Most of them are ferocious,” added Vincent gravely. “I told you it was better than any novel!” cried Lilian, ecstatically. Vincent seemed transfigured--indifferent to the impression he was making. He was extraordinarily grave and went on in a lower tone as if he were talking to himself: “The most astonishing discovery of recent times--at any rate the one that has taught me most--is the discovery of the photogenic apparatus of deep-sea creatures.” “Oh, tell us about it!” cried Lilian, letting her cigarette go out and her ice melt on her plate.