( ( ( ( ( ( ( Place ( ( ( ( 2 to ) 3 ) g ) ( of ( plant tissue ) ) ) ) ( in ( the mortar ) ) ) , ) ( cover ( with ( liquid nitrogen ) ) ) ) and ) ( grind ( to ( a ( fine powder ) ) ) ) ) . )
(ROOT (S (VP (VP (VB Place) (NP (NP (QP (CD 2) (TO to) (CD 3)) (NN g)) (PP (IN of) (NP (NN plant) (NN tissue)))) (PP (IN in) (NP (DT the) (NN mortar)))) (, ,) (VP (VB cover) (PP (IN with) (NP (JJ liquid) (NN nitrogen)))) (CC and) (VP (VB grind) (PP (TO to) (NP (DT a) (JJ fine) (NN powder))))) (. .)))
Place 2 to 3 g of plant tissue in the mortar, cover with liquid nitrogen and grind to a fine powder.
(ROOT (S (NP (NN Ground) (NN tissue)) (VP (VBZ makes) (PRT (RP up)) (NP (NP (JJS most)) (PP (IN of) (NP (NP (DT the) (NN inside)) (PP (IN of) (NP (DT a) (NN plant))))))) (. .)))