The doctor accepted quite readily the theory that Mrs. Vandemeyer had accidentally taken an overdose of chloral.
( ( The doctor ) ( ( ( ( accepted ( quite readily ) ) ( the theory ) ) ( that ( ( Mrs. Vandemeyer ) ( ( had accidentally ) ( taken ( ( an overdose ) ( of chloral ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN doctor)) (VP (VBD accepted) (ADVP (RB quite) (RB readily)) (NP (DT the) (NN theory)) (SBAR (IN that) (S (NP (NNP Mrs.) (NNP Vandemeyer)) (VP (VBD had) (ADVP (RB accidentally)) (VP (VBN taken) (NP (NP (DT an) (NN overdose)) (PP (IN of) (NP (NN chloral))))))))) (. .)))
Mrs. Vandemeyer may have been trying to kill herself. 
( ( Mrs. Vandemeyer ) ( ( may ( have ( been ( trying ( to ( kill herself ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Mrs.) (NNP Vandemeyer)) (VP (MD may) (VP (VB have) (VP (VBN been) (VP (VBG trying) (S (VP (TO to) (VP (VB kill) (NP (PRP herself))))))))) (. .)))