On reflection, the parts will hold together.
( ( On reflection ) ( , ( ( the parts ) ( ( will ( hold together ) ) . ) ) ) )
(ROOT (S (PP (IN On) (NP (NN reflection))) (, ,) (NP (DT the) (NNS parts)) (VP (MD will) (VP (VB hold) (ADVP (RB together)))) (. .)))
The parts will not hold together. 
( ( The parts ) ( ( ( will not ) ( hold together ) ) . ) )
(ROOT (S (NP (DT The) (NNS parts)) (VP (MD will) (RB not) (VP (VB hold) (ADVP (RB together)))) (. .)))