「・・・」。
"Just a... sample." I preserved a portion in a petri dish.
Literal
"A-bit... sample." Petri-dish [to-に] one-part [object-を] preserved.
Dialogue mixed with narration. シャーレ is a loanword from German 'Schale' (dish), the standard Japanese term for a petri dish — a good example of how Japanese scientific vocabulary borrows from multiple European languages, not just English. ちょっと trails off with the ellipsis, suggesting hesitation or understatement. 一部を保存した is clinical, factual narration.