@diemuttergans answered from HERE:
Tenenbaum heard the child entered, her gaze never leaving the specimen jar before her; this was the closest she had come to have the slugs reproducing on their own, and it had died before it’s embryos were even worth harvesting. She would need to try again, be more careful, focus every little bit of attention on–
A tree? Brigid blinked herself out of her thoughts, turning to face the child who gazed up at her with unnaturally bright eyes. “…why would you be interested in something like this? You can see trees in your books. They are no different.”
The boy was pretty certain that wasn’t true. ‘Trees’ in books were little. They were green and brown and they were in ‘sun’. There wasn’t ‘sun’ in the city. Which meant the ‘trees’ had to be different. The pictures in the books sometimes had people next to the ‘trees’, to show how big they were. But it was impossible for something to be that big and still alive. Buildings were big. Only because they were made of steal and glass. ‘Trees’ must look different in real life than in books.
“Have you seen ‘trees’ Mama Tenenbaum? If you won’t let me see ‘trees’ can you tell me about ‘trees’? If I am careful and come back can I go see ‘trees’ by myself? The books say that ‘trees’ need ‘sun’. How do they live if there isn’t ‘sun’? Are you able to concentrate when I ask you so many questions Mama Tenenabum? Can you answer my questions Mama Tenenbaum? Mama Tenenbaum. Mama Tenenbaum. Why can’t I go see ‘trees’?”
Jack knew he was being what Papa Suchong called, ‘obnoxious’. He was inclined not to care so much though. He’d found that, sometimes, when he was particularly ‘obnoxious’ people were willing to just let him do things rather than put up with the tiny experiment. Than again, it was just as likely to backfire and get him nothing more than The Phrase for his trouble.