Meanwhile we kept sinking into the ooze more and more frequently, deeper and deeper; the insatiable mire would suck at us; and, wriggling, we would slip free. Cook kept falling down and crawling, covered with insect bites, all swollen and soaked, and, dear God, how he would squeal when disgusting bevies of minute, bright-green hydrotic snakes, attracted by our sweat, would take off in pursuit of us, tensing and uncoiling to sail two yards and then another two. I, however, was much more frightened by something else: now and then, on my left (always, for some reason, on my left), listing among the repetitious reeds, what seemed a large armchair but was actually a strange, cumbersome gray amphibian, whose name Gregson refused to tell me, would rise out of the swamp.

‘A break,’ said Gregson abruptly, ‘let’s take a break.’

By a stroke of luck we managed to scramble on to an islet of rock, surrounded by the swamp vegetation. Gregson took off his knapsack and issued us some native patties, smelling of ipecacuanha, and a dozen acreana fruit. How thirsty I was, and how little help was the scanty, astringent juice of the acreana …

‘Look, how odd,’ Gregson said to me, not in English, but in some other language, so that Cook would not understand. ‘We must get through to the hills, but look, how odd – could the hills have been a mirage? – they are no longer visible.’

I raised myself up from my pillow and leaned my elbow on the resilient surface of the rock … Yes, it was true that the hills were no longer visible; there was only the quivering vapor hanging over the marsh. Once again everything around me assumed an ambiguous transparency. I leaned back and said softly to Gregson, ‘You probably can’t see, but something keeps trying to come through.’

‘What are you talking about?’ asked Gregson.

I realized that what I was saying was nonsense and stopped. My head was spinning and there was a humming in my ears; Gregson, down on one knee, rummaged through his knapsack, but found no medicine there, and my supply was exhausted. Cook sat in silence, morosely picking at a rock. Through a rent in his shirtsleeve there showed a strange tattoo on his arm: a crystal tumbler with a teaspoon, very well executed.

‘Vallière is sick – haven’t you got some tablets?’ Gregson said to him. I did not hear the exact words, but I could guess the general sense of their talk, which would grow absurd and somehow spherical when I tried to listen more closely.

Cook turned slowly and the glassy tattoo slid off his skin to one side, remaining suspended in midair; then it floated off, floated off, and I pursued it with my frightened gaze, but, as I turned away, it lost itself in the vapor of the swamp, with a last faint gleam.