By instinct she knew her youth was over. By instinct she knew it was time to Go Up.

The group stood near the Hollow, awaiting her. She ran to them, outwardly as active as ever, though her heart felt dead. The Hollow was like an upturned armpit, formed where the branch joined the trunk. In the Hollow a water supply had collected.

The group was watching a line of termights climb the trunk. One of the termights now and again signalled greetings to the humans. The humans waved back. As far as they had allies at all, the termights were their allies. Only five great families survived among the rampant green life; the tigerflies, the tree-bees, the plantants and the termights were social insects mighty and invincible. And the fifth family was man, lowly and easily killed, not organized as the insects were, but not extinct, the last animal species in all the all-conquering vegetable world.

Lily-yo came up to the group. She too raised her eyes to follow the moving line of termights until it disappeared into the layers of green. The termights could live on any level of the great forest, in the Tips or down on the Ground. They were the first and last of insects; as long as anything lived, the termights and tigerflies would.

Lowering her eyes, Lily-yo called to the group.

When they looked, she brought out Clat's soul, lifting it above her head to show to them.

'Clat has fallen to the green,' she said. 'Her soul must go to the Tips, according to the custom. Flor and I will take it at once, so that we can go with the termights. Daphe, Hy, Ivin, Jury, you guard well the man Haris and the children till we return.'

The women nodded solemnly. Then they came one by one to touch Clat's soul.

The soul was roughly carved of wood into the shape of a woman. As a child was born, so with rites its male parent carved it a soul, a doll, a totem soul-for in the forest when one fell to the green there was scarcely ever a bone surviving to be buried. The soul survived for burial in the Tips.

As they touched the soul, Gren adventurously slipped from the group. He was nearly as old as Toy, as active and as strong. Not only had he power to run. He could climb. He could swim. Further, he had a will of his own. Ignoring the cry of his friend Veggy, he scampered into the Hollow and dived into the pool.

Below the surface, opening his eyes, he saw a world of bleak clarity. A few green things like clover leaves grew at his approach, eager to wrap round his legs. Gren avoided them with a flick of his hands as he shot deeper. Then he saw the crocksock – before it saw him.

The crocksock was an aquatic plant semi-parasitic by nature. Living in hollows, it sent down its saw-toothed suckers into the trees' sap. But the upper section of it, rough and tongue-shaped like a sock, could feed also. It unfolded, wrapping round Gren's left arm, its fibres instantly locking to increase the grip.

Gren was ready for it. With one slash of his knife, he clove the crocksock in two, leaving the lower half to thrash uselessly at him as he swam away.

Before he could rise to the surface, Daphe the skilled huntress was beside him, her face angered, bubbles flashing out silver like fish from between her teeth. Her knife was ready to protect him.

He grinned at her as he broke surface and climbed out on to the dry bank. Nonchalantly he shook himself as she climbed beside him.

'Nobody runs or swims or climbs alone,' Daphe called to him, quoting one of the laws. 'Gren, have you no fear? Your head is an empty burr!'

The other women too showed anger. Yet none of them touched Gren. He was a man child. He was tabu. He had the magic powers of carving souls and bringing babies – or would have when fully grown, which would be soon now.

'I am Gren, the man child!' he boasted to them, thumping his chest. His eyes sought Haris's for approval. Haris merely looked away. Now that Gren was so big, Haris did not cheer him on as once he had, though the boy's deeds were braver than before.

Slightly deflated, Gren jumped about, waving the strip of crocksock still wrapped round his left arm. He called and boasted at the women to show how little he cared for them.

'You are a baby yet,' hissed Toy. She was ten, his senior by one year. Gren fell quiet. The time would come to show them all that he was someone special.

Scowling, Lily-yo said, 'The children grow too old to manage. When Flor and I have been to the Tips to bury Clat's soul, we shall return and break up the group. Time has come for us to part. Guard yourselves!'

She saluted them and turned about with Flor beside her.

It was a subdued group that watched their leader go. All knew that the group had to split; none cared to think about it. Their time of happiness and safety – so it seemed to all of them – would be finished, perhaps for ever. The children would enter a period of lonely hardship, fending for themselves before joining o'ther groups. The adults embarked on old age, trial, and death when they Went Up into the unknown.

Lily-yo and Flor climbed the rough bark easily. For them it was like going up a series of more or less symmetrically placed rocks. Now and again they met some kind of vegetable enemy, a thinpin or a pluggyrug, but these were small fry, easily despatched into the green gloom below. Their enemies were the termight's enemies, and the moving column had already dealt with the foes in its path. Lily-yo and Flor climbed close to the termights, glad of their company.

They climbed for a long while. Once they rested on an empty branch, capturing two wandering burrs, splitting them, and eating their oily white flesh. On the way up, they had glimpsed one or two groups of humans on different branches; sometimes these groups waved shyly, sometimes not. Eventually they climbed too high for humans.

Nearer the Tips, new dangers threatened. In the safer middle layers of the forest the humans lived, avoided the perils of the Tips or the Ground.

' Now we move on,' Lily-yo told Flor, getting to her feet when they had rested. 'Soon we will be at the Tips.'

A commotion silenced the two women. They looked up, crouching against the trunk for protection. Above their heads, leaves rustled as death struck.

A leapycreeper flailed the rough bark in a frenzy of greed, attacking the termight column. The leapycreeper's roots and stems were also tongues and lashes. Whipping round the trunk, it thrust its sticky tongues into the termights.

Against this particular plant, flexible and hideous, the insects had little defence. They scattered but kept doggedly climbing up, each perhaps trusting in the blind law of averages to survive.

For the humans, the plant was less of a threat – at least when met on a branch. Encountered on a trunk, it could easily dislodge them and send them helplessly falling to the green.

'We will climb on another trunk,' Lily-yo said.

She and Flor ran deftly along the branch, once jumping a bright parasitic bloom round which treebees buzzed, a forerunner of the world of colour above them.

A far worse obstacle lay waiting in an innocent-looking hole in the branch. As Flor and Lily-yo approached, a tigerfly zoomed up at them. It was all but as big as they were, a terrible thing that possessed both weapons and intelligence – and malevolence. Now it attacked only through viciousness, its eyes large, its mandibles working, its transparent wings beating. Its head was a mixture of shaggy hair and armour-plating, while behind its slender waist lay the great swivel-plated body, yellow and black, sheathing a lethal sting in its tail.

It dived between the women, aiming to hit them with its wings. They fell flat as it sped past. Angrily, it tumbled against the branch as it turned on them again; its golden-brown sting flicked in and out.