( ( ( The ( nucleus id ) ) ( surrounded ( by ( a ( double membrane ) ) ) ) ) ( , ( ( called ( the ( nuclear envelope ) ) ) . ) ) )
(ROOT (S (NP (NP (DT The) (NN nucleus) (NN id)) (VP (VBN surrounded) (PP (IN by) (NP (DT a) (JJ double) (NN membrane))))) (, ,) (VP (VBD called) (NP (DT the) (JJ nuclear) (NN envelope))) (. .)))
The nucleus id surrounded by a double membrane , called the nuclear envelope .
(ROOT (S (NP (NNP Nuclear) (NNP enevelope)) (VP (VBZ is) (NP (NP (DT a) (JJ double) (NN membrane)) (PP (IN of) (NP (NP (DT the) (NN nucleus)) (SBAR (WHNP (WDT that)) (S (VP (VBZ encloses) (NP (DT the) (JJ genetic) (NN material))))))))) (. .)))