Seven days’ march took them one hundred and twenty miles east of Yandjali and into the heart of the great rubber district of M’Bonga.

Twenty miles a day ought to have been covered on an average, but they had delayed here and there to shoot, and the extra porters, whose duty it was to carry the trophies, were already in requisition.

It had been forest most of the way, but forest broken by open spaces; they had crossed two great swards of park-like country where the antelope herds moved like clouds, marvellous natural preserves that might have been English but for the tropic haze and heat and the great n’sambya trees with their yellow bell-like blossoms, the m’binas with their bursts of scarlet bloom, the tall feather-palms, and the wild papaws of the adjoining woods.

But in the last two days of the march the forest had thickened and taken a more sombre note; nothing they had come upon heretofore had been quite so wild as this, so luxuriant and tropical. It was the haunt of the rubber vine, that mysterious plant which requires a glass-house atmosphere and a soil especially rich. The great rubber forest of M’Bonga, thousands of square miles in extent, is really composed of two forests joined by an isthmus of woods. Dimly, it is shaped like an hourglass; south of the constriction where the two forests join lies the elephant country for which Berselius was making, and FÉlix had led them so craftily and well, that they struck into the rubber district only fifty miles from the constriction.

In the forest, thirty miles from the elephant ground, lies the Belgian fort M’Bassa. They were making for this place now, which was to be the base from which they would start on the great hunt.

The fort of M’Bassa is not used to-day as a fort, only as a collecting-place for rubber. In the early days it was a very necessary entrenchment for the Belgians, as a tribe almost as warlike as the Zappo Zaps terrorized the districts; but the people of this tribe have long been brought under the blue flag with the white star. They are now “soldiers,” and their savagery, like a keen tool, has been turned to good account by the Government.

In the great forest of M’Bonga the rubber vines are not equally distributed. Large areas occur in which they are not found; only in the most desolate places do they grow. You cannot tame and prune and bring the rubber vine into subjection; it will have nothing to do with the vineyard and the field; it chooses to grow alone.

Everything else comes to its harvest with a joyous face, but the rubber vine, like a dark green snake, fearful of death, has to be hunted for.

Even in the areas of the forest which it frequents, it is only to be found in patches, so the harvesters cannot go in a body, as men do to the harvesting of the corn, or the cotton, or the grape; they have to break up into small parties and these again subdivide, leaving a single individual here and there where the vines are thickest. He, entirely alone, at the mercy of the evil spirits that are in his imagination and the beasts that are in the forest, makes a rude shelter out of boughs and leaves, and sets to work making incisions in the vine and draining them drop by drop of their viscous sap.

Sometimes he sings over this monotonous work, and in the long rains between the intervals of the shower-bath roarings you can hear the ululations of these folk through the drip of the leaves, and at night the spark-like glimmer of their fires dots the reeking gloom.

These are the conditions of the rubber collector’s task, and it is not a task that ever can be finished; year in, year out, it never ceases.

These woods through which FÉlix led them were to the woods near Yandjali what the music of Beethoven is to the music of Mozart.

Immense and gloomy symphonies. The trees were huge, and groaned beneath the weight of lianas cable-thick. At times they had to burst their way through the veils of leaves and vines, the porters losing themselves and calling one to the other, and the head of the expedition halting till the stragglers were collected; at times the ground they trod on was like grease from the cast-down fruit of the plantains that grew here enormous, and sodden, and dismal, showering their fruit in such quantities that the bush-pigs, devour as they might, could never dispose of it all.

On some of the trees, like huge withered leaves, hung bats, and from some of the trees the beard-moss hung yards long, and of a spectral gray; the very weeds trodden underfoot were sappy, and the smell of their squirting juice mixed itself with the smell of decay.

It was not even ground, either; the whole forest would dip down into an unseen valley; you felt yourself going down hill, down, down, and then you knew you were at the bottom of a sub-arboreal valley by the deeper stagnation of the air. Open spaces, when they came, showed little sky, and they were less open spaces than rooms in the surrounding prison.

FÉlix was not leading them through the uttermost depths of this place; he was following the vague indications of a road by which the rubber from M’Bassa was carted to the river.

They were travelling along a highway, in fact, and the dimmest indication of a track where other men have been before is a thing which robs the wilderness of much of its terror.

The loneliness of the forest beyond track or way, in those vast depths where the rubber collectors have to go alone, I leave you to imagine.

At last, at noon, on the third day of their journey to this place they struck rising ground where the trees fell away till no trees were left, and the blue sky of heaven lay above their heads, and before them on the highest point of the rise, Fort M’Bassa burning in the sun.