I didn’t have much issues with these chapters, but am a bit confused about some colloquial phrases.
Near the end of chapter 18
でも、だからこそ精神と肉体とのつりあいがとれるわけだ。だってそうだろ？ 大学程度の学力がある赤ん坊なんて、気持ちが悪いだけじゃないか
With “だってそうだろ？” here, is he asking himself “Why is it so?” before giving the explanation?
The end of chapter 19
なんて、おませなんだろう！
I understand that this is some kind of exclamation expressing surprise, what are these words though? I guess it does not mean “precocious child Nandaro” like Jisho says, and google just returns 時をかける少女 references.
And a little bit before that:
じゃあ、いってしまおう。
Is he talking to himself again here meaning “Well, I’ll just say it!”?
Oh, and by the way, close to the beginning of chapter 18:
医者や科学者は、この状態に驚き、なんとかしようとして研究に研究をかさねた。
Here’s an explanation of the grammar if anyone needs it.