“Isaac?” Lublamai’s yell sailed over the relentless squawks and screeches. Isaac and David looked over at him. He had wandered on past the lasifly and the pair of gild-parakeets. He was pointing at a smaller set of boxes and cases and vats. “What’s all this?”

“Oh, that’s my nursery,” shouted Isaac with a grin. He strode towards Lublamai, pulling David with him. “I thought it might be interesting to see how you progress from something that can’t fly to something that can, so I managed to get hold of a bunch of neonates and unborns and baby things.”

He stopped by the collection. Lublamai was peering into a small hutch at a clutch of vivid cobalt eggs.

“Don’t know what they are,” said Isaac. “Hope it’s something pretty.”

The hutch was on the top of a pile of similar open-fronted boxes, in each of which a clumsy little hand-made nest contained between one and four eggs. Some were astonishing colours, some a drab beige. A little pipe coiled away behind the hutches and disappeared over the railings into the boiler below. Isaac nudged it with his foot.

“I think they prefer it warm . . .” he muttered. “Don’t really know . . .”

Lublamai was bending down to peer into a glass-fronted tank.

“Wow . . .” he breathed. “I feel like I’m ten again! Trade you these for six marbles.”

The tank’s floor writhed with little green caterpillars. They munched voraciously and systematically on the leaves stuffed rudely around them. The stems were crawling with little bodies.

“Yeah, that’s quite interesting. Any day now they should go into their cocoons, and then I think I’m going to ruthlessly cut them open at various stages to see how they transmogrify themselves.”

“Life as a lab assistant is cruel, isn’t it?” murmured Lublamai into the tank. “What other disgusting grubs do you have?”

“Bunch of maggots. Easy to feed. That’s probably the smell that’s got Sincerity upset.” Isaac laughed. “Some other grubs that promise to turn into butterflies and moths, horribly aggressive water-things that I am told turn into damask-flies and what have you . . .” Isaac pointed at a tank full of dirty water, behind the others.

“And,” he said, swaggering over to a little mesh cage some feet away, “something rather special . . .” He jabbed his thumb at the container.

David and Lublamai crowded round. They gazed with open mouths.

“Oh, now that is splendid . . .” whispered David, after a while.

“What is it?” hissed Lublamai.

Isaac peered over their heads at his star caterpillar.

“Frankly, my friends, I have not an arsing clue. All I know is that it’s huge, pretty, and not very happy.”