"Just... Just keep showing him the book. Oh, and it has to be a page with pictures, since he probably can't read. When the experiment seems to drag on, try to draw his attention, like mimicking sounds. I don't need to explain every detail, right?

Yes, I know. It's unfortunate. Pitiful and sad. I do feel human emotions, thank you very much. However, he ultimately survived thanks to this place. I hope he continues to live, in any shape or form. If you're thinking the same thing, it'd be better off if you dropped that guilt right now.
....
Tell the kid today's treat is going to be grape-flavored candy. It's his favorite."